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StoryWorks- Volcano that Changed the World

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StoryWorks- Volcano that Changed the World

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Galveston, Texas, was drowning.

It was September 8, 1900, and the city was being torn to pieces by a brutal hurricane. Thousands of people were dead.

And in the middle of the terror was 14-year-old Harry Maxson.

He stood at the window of his house. Outside, the wild, churning ocean was like a furious beast devouring his neighborhood. It was swallowing up trees and barns, tearing apart houses and carrying them away. Harry's ears pounded with the sounds of the screaming wind and of flying bricks and chunks of shattered wood smashing against the walls of his family's home.
Bam! Bam!
And then Harry heard another sound, a desperate cry rising up over the wind.

"Help me!"

It was a woman, calling from somewhere outside.

Harry wanted to turn away-he could barely swim. How could he possibly help anyone caught in that storm?

"Please! Come and save us!" the woman cried.

Her words seemed to grab hold of Harry's heart.

Harry took a breath, gathering his courage.

He had to try to save that woman . . . even if it cost him his life.

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America's Deadliest Disaster | Narrative Nonfiction | Scholastic Storyworks Magazine

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Galveston, Texas, was drowning. It was September 8, 1900, and the city was being torn to pieces by a brutal hurricane. Thousands of people were dead. And in the middle of the terror was 14-year-old Harry Maxson. He stood at the window of his house.

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What Is a Tornado? | How do tornados form? Tornados for kids

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What is a Blizzard? | Winter Science | Weather Science | SciShow Kids

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Rain & Floods

How does rain form?
Water droplets form from warm air. As the warm air rises in the sky it cools. Water vapor (invisible water in the air) always exists in our air. Warm air holds quite a bit of water. For example, in the summer it is usually very humid. When enough of these droplets collect together, we see them as clouds. If the clouds are big enough and have enough water droplets, the droplets bang together and form even bigger drops. When the drops get heavy, they fall because of gravity, and you see and feel rain.

What causes rain?

When clouds develop or rain occurs, something is making the air rise. Several things can make this happen. Mountains, low-pressure areas, cold fronts, and even the jet stream.

How big are raindrops?
Raindrops are much smaller than we think! They are actually smaller than a centimeter. Raindrops range from 1/100 inch (.0254 centimeter) to 1/4 inch (.635 centimeter) in diameter.

How fast do raindrops fall?
Not including wind-driven rain, raindrops fall between 7 and 18 miles per hour (3 and 8 meters per second) in still air. The range in speed depends on the the size of the raindrop. Air friction breaks up raindrops when they exceed 18 miles per hour.

What is a flood?
A flood results from days of heavy rain and/or melting snows, when rivers rise and go over their banks.

What is a flash flood?
A flash flood is sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain. They often occur after intense rainfall from slow moving thunderstorms. In narrow canyons and valleys, floodwaters flow faster than on flatter ground and can be quite destructive.

Do flash floods hurt people?
Flash floods are the #1 weather-related killer in the U.S. Nearly 80% of flash flood deaths are auto related. Know beforehand if your area is a flood risk.

How much water is needed for your car to float away?
A mere 2 feet of water can float a large vehicle or even a bus. This is why you should never drive through flooded roads. Just 6 inches of rapidly moving flood water can knock a person down.

What is a monsoon?
A monsoon is a seasonal wind, found especially in Asia that reverses direction between summer and winter and often brings heavy rains. In the summer, a high pressure area lies over the Indian Ocean while a low exists over the Asian continent. The air masses move from the high pressure over the ocean to the low over the continent, bringing moisture-laden air to south Asia. During winter, the process is reversed and a low sits over the Indian Ocean while a high lies over the Tibetan plateau so air flows down the Himalaya and south to the ocean. The migration of trade winds and westerlies also contributes to the monsoons. Smaller monsoons take place in equatorial Africa, northern Australia, and, to a lesser extent, in the southwestern United States.

What is radar?
Radar is an electronic instrument, which determines the direction and distance of objects that reflect radio energy back to the radar site. It stands for Radio Detection and Ranging. This is what meteorologists use to see rain or snow.

What is Doppler Radar? Doppler Radar detects precipitation intensity, wind direction and speed, and provides estimates of hail size and rainfall amounts. Doppler Radar gives forecasters the capability of providing early detection of severe thunderstorms that may bring strong damaging winds, large hail, heavy rain, and possibly tornadoes. Combined with satellites, radar gives forecasters the ultimate tools to provide accurate forecasts and advanced severe weather warnings.

Doppler Radar gets its name from the Doppler Effect. Have you ever listened to a train whistle as it was coming toward you? You probably noticed that the pitch of the whistle changed as the train passed you and moved away. This change in the frequency of sound is called the Doppler Effect. Doppler Radar measures the changes in the frequency of the signal it receives to determine the wind. How does Doppler Radar work?

The National Weather Service has installed a new type of Doppler Radar called NEXRAD Radar. NEXRAD stands for Next Generation Radar. This radar produces many different views of storms and rain that allows meteorologists to determine if a storm could be severe.
What is NEXRAD Radar?

Know the Lingo

FLOOD WATCH - means that an overflow of water from a river is possible for your area.

FLASH FLOOD WATCH - means that flash flooding is possible in or close to the watch area. Flash Flood Watches can be put into effect for as long as 12 hours, while heavy rains move into and across the area.

FLOOD WARNING - means flooding conditions are actually occurring in the warning area.

FLASH FLOOD WARNING - means that flash flooding is actually occurring in the warning area. A warning can also be issued as a result of torrential rains, a dam failure or snow thaw.
Click Here to see if there are any active warnings in your area.
Flood Safety Tips

BEFORE A FLOOD: Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food, can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water.
DURING A FLOOD: Move to a safe area quickly. Move to higher ground, like the highest floor of your home. Avoid areas subject to sudden flooding like low spots and canyons. Avoid already flooded areas. If a flowing stream of water is above your ankles stop, turn around and go the other way. Do not attempt to drive through a flooded road. The depth of the water is not obvious and the road may be washed away. If your car stalls, leave it and seek higher ground. Rapidly rising water may engulf the car, pick it up and sweep it away. Kids should never play around high water, storm drains or viaducts. Be cautious at night, because its harder to see flood dangers. If told to evacuate, do so immediately.
AFTER THE FLOOD: Always, boil drinking water. Electrical equipment should be checked and dried before used.
Rain Activities

Lesson Plan: Here is a great lesson plan on learning about precipitation. In this activity, kids will use a weather map to answer questions about precipitation falling across the country. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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Facts Just for Kids, Teachers and Parents

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3.Floods can last for minutes, hours, days, or weeks. Some floods can last even longer, depending on the region, climatic conditions, etc.

4.Being close to water bodies increases the risk of flooding. Villages, towns, and cities located close to rivers, seas, and oceans are more susceptible to floods.

5.Floods can occur in one part of the city or throughout the state.

6.There are five different types of flooding and they are aerial, catastrophic, coastal, riverine and urban flooding.

7.Aerial flooding is caused by heavy or . The excess water gets collected in a low-lying area and starts to overflow.

8.Catastrophic flooding is caused by infrastructure failure, like the failure of a levee or dam.

9.Coastal flooding is caused by rising sea levels, like a storm surge caused by a . Regions on the coastline (in any country) are at a high risk of this type of flooding.

10.Riverine (Channel) flooding is caused by water overflowing from a lake, pond, river or stream. It is the most common type of flooding.

11.Urban flooding is caused by a drainage system or a storm sewer system that is overwhelmed. It can also happen when the hard concrete/ asphalt surfaces prevent the earth from absorbing the excess water.

12.A flash flood is the sudden and rapid flooding of an area that is prone to flooding. It can happen in a few minutes or hours and are dangerous for humans and animals alike.

13.Flash floods are caused by heavy rain, hurricanes, severe thunderstorms , tropical storms or melting snow.

14.Flash floods occur in hilly regions and dry riverbeds where water quickly accumulates in a place.
Flood Safety Planning and Alerts

A flash flood watch is a weather alert issued by the National Weather Service. The NWS issues this type of weather alert when the conditions are right for flash flooding.

A flash flood warning is a weather alert issued by the National Weather Service. The NWS issues this type of weather alert when a flash flood is occurring or is imminent.

The NWS sends out advice to 'turn around, don't drown', which means it asks people to move to drier or high-lying areas on their side instead of trying to cross a flood and reach the other side.

The Association of State Floodplain Managers in the US educates people and promotes policies that can mitigate the risk of floods without affecting the natural balance in the environment.

Governments and local authorities build levees, reservoirs, bunds, and weirs, apart from dams, to stop the overflowing water from rivers and lakes from entering the towns and cities.

Maintaining wetlands and cleaning natural drainage systems can reduce the risk of floods in the region.

Redesigning the infrastructure and installing rain barriers are other ways to mitigate the causes of floods.

Beavers are little mammals that build natural dams to stop the water flow. They have a prominent role in controlling floods in high-risk areas.

Technology like artificial intelligence and machine learning help accurately predict floods in advance and take the necessary action to minimize losses.

Impact of Floods on Our Lives

Damage caused by flooding can reach into the billions of dollars. Floods kill more people compared to other natural disasters.

Around 90% of all the natural disaster declarations in the United States are related to some sort of flooding.

The northeast and Midwest regions in the US are most affected by floods.

The time between the spring and fall see a majority of floods in the US, though they can occur throughout the year.

Many automobile vehicles can float in as little as one foot of water during a flood. One should never drive into a flooding area.

As little as two feet of rushing flood water can carry away an automobile, including a pick-up truck or SUV.

Flood waters have a fast-moving current. People can lose their balance in just six inches of water.

People are asked to evacuate to safer places during floods. They take a few personal belongings and move to temporary homes until the floods subside.

The shelter homes are set up by the local government (and NGOs) to provide aid to the flood victims.

Floods pollute drinking water sources and lead to water-borne diseases like cholera, hepatitis, typhoid, etc.

Floods dump the waste (debris) back on land. This can include plastic, metal, and hazardous chemicals previously released into the water bodies.

Though floods occur mostly in plains and low-lying areas, they can wreak havoc even on plateaus if the infrastructure doesn't have a proper drainage system for excess water to flow into the nearest water body.

Countries like China, Bangladesh, and India have the highest exposure to floods due to their long coastlines.

Biggest Floods in History - Top 5 Floods That Caused Massive Destruction

China faced the Yellow River Floods in 1887. The floods killed 900,000 people on 28th September when the river water overflowed into the surrounding areas. The floods covered 19305.108 square miles and made more than two million people homeless.

The Yellow River floods occurred in 1938 yet again and caused a loss of 800,000 million lives (or more). However, this flood was created (man-made) by the Chinese Nationalist Government during the second Sino-Japan War to prevent the Japanese forces from marching ahead. Sadly, the Japanese forces were unaffected by the floods, while the Chinese died.

In 1975 in China, the Banqiao Reservoir Dam on the River Hu was destroyed by Typhoon Nina. The dam weakened and broke, resulting in water lashing out at the surrounding towns and cities. Half of China was said to be flooded because of this. The death tally crossed 160,000 people, and many millions got stuck underwater.

The deadliest flood on record was the 1939 floods, also known as the 1931 Yangtze-Huai River floods. Some estimates have the toll as high as four million people. This flood is also considered the deadliest natural disaster in recorded history.

St. Felix's Flood in the Netherlands in 1530 occurred on 5th November. More than 120,000 people were killed by the flood that washed away most of the land. The Dutch went on to name it Evil Saturday or Kwade Zaterdag. The regions of modern-day Flanders, Reimerswaal cities, and Zeeland became salt marshes as a result of the flood.

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These facts about floods for kids will help you with home assignments or help teachers with preparing classes for their students. The list of

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Most often flooding is caused by heavy rains over a long period of time. After a lot of rain, the ground becomes full of water, and new rainwater runs off, or flows downhill. That runoff goes directly into streams and rivers. In springtime the rain may be combined with melting snow. Because of the extra water flowing into the streams and rivers, their water level rises. If the level rises so much that the water overflows the banks, a flood occurs.

Flooding can be worse if there is not much vegetation (trees, grass, and other plants) on the land around rivers. In general, land that has little vegetation is less able to absorb water. The result is a larger amount of water entering a river system.

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When water overflows onto dry land, a flood takes place. Floods have always been a part of life on Earth. Almost every culture has a legend about a great flood. Since ancient...

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A flood is an overflow of water on normally dry ground. This is most commonly due to an overflowing river, a dam break, snowmelt, or heavy rainfall. Less commonly happening are tsunamis, storm surge.

The most deadly flooding was in 1931 in China and killed between 2,000,000 and 4,000,000 people. The Kerala flood in India was another flood that has destroyed people's houses.

During a flood, people try to move themselves and their most precious belongings to higher ground quickly. The process of leaving homes in search of a safe place is called flood evacuation.

Bangladesh is the most flood prone area in the world.

Pollution of drinking water

During a flood there is plenty of water logging and overflow of water, but it is mostly polluted and not safe to drink. If people drink this dirty water, they may suffer from diseases such as typhoid and cholera, hepatitis and other such diseases. People can get ready to survive a flood by filling many containers with fresh and clean drinking water and storing other emergency supplies; like: medicine and food. During flood people try to go to higher sides because the flood water wouldn't reach high areas. Also drains overflow and mix with clean water and people who drink it might fall ill.

Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more rapidly than it can either infiltrate or run off. The excess accumulates in place, sometimes to hazardous depths. Surface soil can become saturated, which effectively stops infiltration, where the water table is shallow, such as a floodplain, or from intense rain from one or a series of storms. Infiltration also is slow to negligible through frozen ground, rock, concrete, paving, or roofs. Areal flooding begins in flat areas like floodplains and in local depressions not connected to a stream channel, because the velocity of overland flow depends on the surface slope. Endorheic basins may experience areal flooding during periods when precipitation exceeds evaporation.

Riverine (Channel)

Floods occur in all types of river and stream channels, from the smallest ephemeral streams in humid zones to normally-dry channels in arid climates to the world's largest rivers. When overland flow occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load. Localized flooding may be caused or exacerbated by drainage obstructions such as landslides, ice, debris, or beaver dams.

Slow-rising floods most commonly occur in large rivers with large catchment areas. The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be very intense in smaller areas of those basins.

Rapid flooding events, including flash floods, more often occur on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, or normally-dry channels. The cause may be localized convective precipitation (intense thunderstorms) or sudden release from an upstream impoundment created behind a dam, landslide, or glacier.

Flash floods are the most common flood type in normally-dry channels in arid zones, known as arroyos in the southwest United States and many other names elsewhere. In that setting, the first flood water to arrive is depleted as it wets the sandy stream bed. The leading edge of the flood thus advances more slowly than later and higher flows. As a result, the rising limb of the hydrograph becomes ever quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant.

Estuarine and coastal

Flooding in estuaries is commonly caused by a combination of storm surges caused by winds and low barometric pressure and large waves meeting high upstream river flows.

Coastal areas may be flooded by storm surges combining with high tides and large wave events at sea, resulting in waves over-topping flood defenses or in severe cases by tsunami or tropical cyclones. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category. Research from the NHC (National Hurricane Center) explains: "Storm surge is an additional rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with spring tide, resulting in storm tides reaching up to 20 feet or more in some cases."

Urban flooding

Catastrophic

Catastrophic riverine flooding is usually associated with major infrastructure failures such as the collapse of a dam, but they may also be caused by drainage channel modification from a landslide, earthquake or volcanic eruption. Examples include outburst floods and lahars. Tsunamis can cause catastrophic coastal flooding, most commonly resulting from undersea earthquakes.

Causes of floods

Flooding is usually caused when a volume of water within a water body, such as a lake, overflows outside it. Sometimes if a dam breaks, it suddenly releases a large amount of water. The result is that some of the water travels to land, and 'floods' the area. Many rivers are in a channel, between river banks. They flood when the strength of the river causes it to flow beyond the banks. This is more common at bends or meanders.

Flood damage can be prevented by moving away from places that flood. However, people have long liked to have their homes and businesses alongside water because water is good for agriculture and transport and in other ways. Floods are also caused due to improper management of drains.

Rainfall is the most common cause. Snow melt is also a cause of flooding. Tsunamis and Storm Surge are less common ways that floods happen. Coastal Flooding is another common cause of flooding, and this is caused by low pressure systems or storms.

Flood safety planning

In the United States, the National Weather Service gives out the advice "Turn Around, Don't Drown" for floods; that is, it recommends that people get out of the area of a flood, rather than trying to cross it. At the most basic level, the best defense against floods is to seek higher ground for high-value uses while balancing the foreseeable risks with the benefits of occupying flood hazard zones. Critical community-safety facilities, such as hospitals, emergency-operations centers, and police, fire, and rescue services, should be built in areas least at risk of flooding. Structures, such as bridges, that must unavoidably be in flood hazard areas should be designed to withstand flooding. Areas most at risk for flooding could be put to valuable uses that could be abandoned temporarily as people retreat to safer areas when a flood is imminent.

Planning for flood safety involves many aspects of analysis and engineering, including:

observation of previous and present flood heights and inundated areas,

statistical, hydrologic, and hydraulic model analyses,

mapping inundated areas and flood heights for future flood scenarios,

long-term land use planning and regulation,

engineering design and construction of structures to control or withstand flooding,

intermediate-term monitoring, forecasting, and emergency-response planning, and

short-term monitoring, warning, and response operations.

Each topic presents distinct yet related questions with varying scope and scale in time, space, and the people involved. Attempts to understand and manage the mechanisms at work in floodplains have been made for at least six millennia.

In the United States, the Association of State Floodplain Managers works to promote education, policies, and activities that mitigate current and future losses, costs, and human suffering caused by flooding and to protect the natural and beneficial functions of floodplains - all without causing adverse impacts. A portfolio of best practice examples for disaster mitigation in the United States is available from the Federal Emergency Management Agency.

In many countries around the world, waterways prone to floods are often carefully managed. Defenses such as detention basins, levees, bunds, reservoirs, and weirs are used to prevent waterways from overflowing their banks. When these defenses fail, emergency measures such as sandbags or portable inflatable tubes are often used to try to stem flooding. Coastal flooding has been addressed in portions of Europe and the Americas with coastal defenses, such as sea walls, beach nourishment, and barrier islands.

In the riparian zone near rivers and streams, erosion control measures can be taken to try to slow down or reverse the natural forces that cause many waterways to meander over long periods of time. Flood controls, such as dams, can be built and maintained over time to try to reduce the occurrence and severity of floods as well. In the United States, the U.S. Army Corps of Engineers maintains a network of such flood control dams.

In areas prone to urban flooding, one solution is the repair and expansion of man-made sewer systems and stormwater infrastructure. Another strategy is to reduce impervious surfaces in streets, parking lots and buildings through natural drainage channels, porous paving, and wetlands (collectively known as green infrastructure or sustainable urban drainage systems (SUDS)). Areas identified as flood-prone can be converted into parks and playgrounds that can tolerate occasional flooding. Ordinances can be adopted to require developers to retain stormwater on site and require buildings to be elevated, protected by floodwalls and levees, or designed to withstand temporary inundation. Property owners can also invest in solutions themselves, such as re-landscaping their property to take the flow of water away from their building and installing rain barrels, sump pumps, and check valves.

In some areas, the presence of certain species (such as beavers) can be beneficial for flood control reasons. Beavers build and maintain beaver dams which will reduce the height of flood waves moving down the river (during periods of heavy rains), and will reduce or eliminate damage to human structures, at the cost of minor flooding near the dams (often on farmland). Besides this, they also boost wildlife populations and filter pollutants (manure, fertilisers, slurry). UK environment minister Rebecca Pow stated that in the future the beavers could be considered a "public good" and landowners would be paid to have them on their land.

Related pages

Images for kids

A dog sitting on top of 2 feet of mud deposited by flooding in the 2018 Kerala floods in India. Flooding not only creates water damage, but can also deposit large amounts of sediment.

Minor flooding in a parking lot off Juniper street Atlanta on Christmas Eve from thunderstorms caused by an El Nino event. The same El Nino caused recorded highs for January in Atlanta

Flash flooding caused by heavy rain falling in a short amount of time.

Dozens of villages were inundated when rain pushed the rivers of northwestern Bangladesh over their banks in early October 2005. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured the top image of the flooded Ghaghat and Atrai Rivers on October 12, 2005. The deep blue of the rivers is spread across the countryside in the flood image.

In Spanish: Inundación para niños

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How Floods Form

In 2002, heavy rains in Texas caused a reservoir to overflow. The raging water cleared everything in its path including trees, boulders ... a bridge! In just three days, the floodwaters carved a 1.4 mile (2.2 kilometers) long, nearly 20-foot-(6 meters)-deep canyon.

A flood is a rise of water with no place to go. Floods come in all depths, from just a couple inches to many feet. The power of floodwater is extraordinary and lethal. In less than an hour, strong rain can turn an ankle deep creek into an unstoppable 30-foot-high swell that overpowers everything in its path.

Floods occur all over the world. Causes of floods include hurricanes, broken levees or dams, rapidly thawing snow, ice jams, and heavy slow moving rain or repeated rains. A flood can happen in a few minutes, hours, days, or over weeks.

No matter how quickly it happens or the cause, flooding is deadly. Floods kill more people and causes more damage than other severe weather related events. Many die trying to drive or walk through a flooded area. Just six inches of water can knock a person off their feet. Just two feet of water can carry a car away.

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In 2002, heavy rains in Texas caused a reservoir to overflow. The raging water cleared everything in its path including trees, boulders ... a bridge! In just three days, the floodwaters carved a 1.4 mile (2.2 kilometers) long, nearly 20-foot-(6 meters)-deep canyon. A flood is a rise of water with no place to go.

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Sinkholes can be the stuff of nightmares: the ground suddenly opens up to swallow a car, a home or an entire block. But such extreme damage, formally referred to as "catastrophic ground cover collapse" in insurance parlance, is actually quite rare.

Instead, sinkholes are generally smaller depressions that may become a pricey nuisance rather than a life-threatening disaster.

What's a sinkhole?

Sinkholes typically form when naturally acidic rainwater erodes underlying bedrock, creating damage beneath the surface. Their formation is most common in easily erodible karst terrains with carbonate rocks, like limestone or dolomite, or minerals known as evaporites, like salt and gypsum.

When groundwater seeps into cracks and then pools beneath the surface, it wears away these rocks and leads to the formation of underground caves and other openings. Soil particles fall into these gaps too, enlarging the chasms and facilitating the collection of more water.

A sinkhole forms when these chewed-up sublayers can no longer support surface sediments hovering over the void left by erosion. Usually, little or no change is noticeable from above as this destructive process is underway, which could take hundreds or thousands of years. Drought or heavy rain can exacerbate sinkhole risk, as can human activities like heavy pumping of groundwater or construction.

There are two types of sinkholes: Slow-growing cover-subsidence sinkholes are the most common, but cover-collapse sinkholes can appear in just a matter of hours and are triggered in roughly the same way as their slower-growing counterparts-collapsing when the roof of a cave becomes too thin to support the weight above.

Where do sinkholes occur?

Most reported damage from sinkholes in the U.S. occurs in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania, according to the U.S. Geological Survey. Florida is particularly known for its sinkholes since its sandy soil sits atop its Swiss cheese-like limestone.

There's no database for sinkholes in the U.S. so there's no comprehensive count of how many sinkholes form each year, but the Geological Survey suggests the price tag for known damage from the formations amounts to some $300 million annually. Much of that damage is to highways, other roads and buildings. Yet these costs are lower than those of other natural hazards including hurricanes, tornadoes, flooding, earthquakes and wildfires-all events that usually leave more than $1 billion of damage in their wake each year.

Florida's Department of Environmental Protection notes sinkhole risk assessments remain challenging since expensive geophysical survey techniques or test drilling are the only ways to detect underground cavities. Rarely, sinkholes are presaged by cracks or slumping.

Other locales with known sinkholes include the Dead Sea, since salt also easily breaks down, and Mexico's Yucatan Peninsula, which is often riddled with sinkholes due to its limestone.

What do sinkholes look like?

Sinkhole sizes vary dramatically-they can be a few feet or stretch to hundreds of acres. Their depth varies too: Some are less than one foot deep whereas others are more than 100 feet.

Sinkholes can look like shallow bowls or like a collapsed void with steep, vertical walls. When water collects in sinkholes, sometimes ponds are formed.

Sinkhole attractions

Some sinkholes have also become tourist attractions. In February 2014, for example, a sinkhole opened up overnight and swallowed classic cars at the National Corvette Museum in Bowling Green, Kentucky. No one was in the building at the time, but security cameras caught the incident on camera. The incident subsequently fueled tourism and the museum opened up a dedicated exhibit two years later.

The world's biggest known sinkhole is China's Xiaozhai Tiankeng which is both the deepest and largest sinkhole in the world. It's more than 2,000-feet long and extends roughly the same distance downward. The word Tiankeng means "The Heavenly Pit." The sinkhole's home to more than 1,000 types of animals and plants, including the clouded leopard, according to the Chinese government, and a huge staircase has been built inside the sinkhole to help facilitate area tourism.

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They can be a life-threatening disaster-or a pricey nuisance. Here's what you need to know about the depressions and holes that can form beneath our feet.

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Dr Karl digs deep into sinkhole science

A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area. Heavy localised rainfall or large areas of concreted ground can change the natural water flow.

In May 2010, a giant sinkhole opened up in Guatemala City in Central America. The deep hole (which formed an almost perfect cylinder 20m wide and 30m deep!) swallowed an entire three-storey building! This sinkhole was caused by water shifting the ground's underlying layer of weak volcanic rock.

Last year a small sinkhole formed in the backyard of a family home in Illawong, a suburb of Sydney. A man and his baby were sitting on the couch, when the ground suddenly fell away from beneath them. The collapse was accompanied by a big explosion of dirt, which knocked over a tall tree and a washing line!

About one tenth of the Earth's surface is susceptible to sinkholes, but don't panic - the likelihood of one opening up near you is very small!
In next month's issue, we'll be aiming high and exploring how planes fly!
DID YOU KNOW? The world's deepest sinkhole was in Chongqing, China, reaching down a whopping 662 metres!

DID YOU KNOW? Sinkholes are so common in Florida, USA, that until 2007 it was compulsory for home owners to have Sinkhole Insurance!

DID YOU KNOW? The local geology of Mt. Gambier in South Australia makes it very prone to sinkholes. Luckily, the fairly constant water table and dry conditions have stopped massive numbers of sinkholes from forming.

DID YOU KNOW? The areas of Australia most susceptible to sinkholes include parts of Canberra, Newcastle and Perth, as well as western New South Wales and the Nullabor region.

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sinkholes | science with dr karl | national geographic kids

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Dr Karl digs deep into sinkhole science A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area.

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Dr Karl digs deep into sinkhole science

A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area. Heavy localised rainfall or large areas of concreted ground can change the natural water flow.

In May 2010, a giant sinkhole opened up in Guatemala City in Central America. The deep hole (which formed an almost perfect cylinder 20m wide and 30m deep!) swallowed an entire three-storey building! This sinkhole was caused by water shifting the ground's underlying layer of weak volcanic rock.

Last year a small sinkhole formed in the backyard of a family home in Illawong, a suburb of Sydney. A man and his baby were sitting on the couch, when the ground suddenly fell away from beneath them. The collapse was accompanied by a big explosion of dirt, which knocked over a tall tree and a washing line!

About one tenth of the Earth's surface is susceptible to sinkholes, but don't panic - the likelihood of one opening up near you is very small!
In next month's issue, we'll be aiming high and exploring how planes fly!
DID YOU KNOW? The world's deepest sinkhole was in Chongqing, China, reaching down a whopping 662 metres!

DID YOU KNOW? Sinkholes are so common in Florida, USA, that until 2007 it was compulsory for home owners to have Sinkhole Insurance!

DID YOU KNOW? The local geology of Mt. Gambier in South Australia makes it very prone to sinkholes. Luckily, the fairly constant water table and dry conditions have stopped massive numbers of sinkholes from forming.

DID YOU KNOW? The areas of Australia most susceptible to sinkholes include parts of Canberra, Newcastle and Perth, as well as western New South Wales and the Nullabor region.

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sinkholes | science with dr karl | national geographic kids

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Dr Karl digs deep into sinkhole science A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area.

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What are sinkholes?
Sinkholes are pits in the ground that form in areas where water gathers without external drainage. Sinkholes mainly occur as water drains below ground. It can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.

What causes sinkholes?
Sinkholes can be natural or man made. Natural sinkholes occur due to erosion or underground water. They start developing long time before it actually appears. The ground beneath our feet is not as much of a solid structure as we think it is. The ground is made from dirt, along with many rocks and minerals. There is water continually seeping in between the mud, rocks and minerals, as it makes its way down to the ground water reservoirs. As this happens, the water slowly erodes the rocks and minerals. Sometimes the flow of water increases to a point when it washes away the underground structure of the land. And when the structure becomes too weak to support the surface of the earth, it collapses and opens up a hole. This is how sinkholes are formed.

What type of bedrock is more susceptible to sinkholes?
Areas that have a bedrock made of limestone, salt deposits or carbonate rock are most susceptible to erosion and the formation of such holes. These rocks tend to erode as acidic water passes through them. When rainwater passes through decaying plant debris, it tend to become more acidic. Over a period of years, overlying sediments collapse and a sinkhole develops. Sometimes the holes are small, measuring a few feet wide and ten to fifteen feet deep. Others can be hundreds of miles wide and deep. However, all of them can be dangerous for those that get caught in them. There are three major kinds of sinkholes. Their formation is determined by the same geological processes, barring a few differences.

Can humans cause sinkholes?
Yes! Humans are also responsible for the formation of sinkholes. Activities like drilling, mining, construction, broken water or drain pipes, improperly compacted soil after excavation work or even heavy traffic can result in small to large sinkholes. Water from broken pipe can penetrate through mud and rocks and erode the ground underneath and cause sinkholes. Sometimes, heavy weight on soft soil can result in collapse of ground, resulting in a sinkhole. Sinkholes can also form when the land surface is changed.

How quickly do sinkholes form?
Most of the time, sinkholes form gradually. Occasionally, though, the collapse is sudden. Those sudden sinkholes are often the ones that open up and swallow cars, homes and streets.

Why are there so many sinkholes?
Most of the sinkholes we are seeing at the moment are at least indirectly created by human activity. They're occuring just to the sides of human constructions where rain water has been concentrated on a particular patch of ground in the form of run-off from roofs and tarmac. However, these local factors wouldn't matter if it wasn't for the wider picture. The Southeast, where most of the sinkholes have appeared, has not only suffered one of the wettest winters in recent decades, but is also natural sinkhole country as most of the bedrock is the soluble chalk.

What are some notable sinkholes?
In 2010 one of the most devastating sinkholes in recent times hit Guatemala City. An area approximately 65ft wide and 100ft deep collapsed, swallowing a three-story factory and killing 15 people. The sinkhole was caused by a number of factors including an influx of water from Tropical Storm Agatha and leakage from a local sewerage pipe.

On February 12, 2014, a sinkhole some 40ft wide and 20ft deep opened under the floor of the Skydome area of the National Corvette Museum causing a portion of the floor to collapse. Eight rare and one-of-a-kind Corvettes, portions of the display stands and rails, large concrete floor slabs and dirt fell into the sinkhole, causing serious damage to some of the Corvettes. The Corvettes involved have an estimated value of a million dollars.

Do sinkholes happen in other parts of the world?
Yes! The deepest we know about is the Xiaozhai tiankeng in China. Tiankeng is the local term for large sinkholes and translates literally as 'heavenly pit'. This particular example in the Chongqing district is a staggering 662m deep and 626m wide.

Other notable sinkholes include Sima Humboldt in Bolivia, a crater 314m deep and formed from extremely resistant sandstone.

The Great Blue Hole in Belize, a perfectly round hole in the middle of an atoll which is 124m deep.

Finally, Crveno Jezero in Croatia, a 530m deep sinkhole with nearly vertical walls.

How many types of sinkholes are there?
The three major types of sinkholes know to us are : Solution, Cover Collapse and Cover Subsidence.

Solution sinkholes are most commonly seen in areas that have a very thin cover of soil on the surface, exposing the bedrock below to continual erosion by water. As the water percolates through the bedrock, it carries away small parts of the rock with it. As the bedrock erodes, particles collect in the spaces it leaves. Over a period of time, a small depression is formed. It is at this point where the hole forms. The hole is usually bowl shaped and can be quite large. Sometimes the bedrock may collapse all of a sudden to form such a solution sinkhole and other times it happens over time.

The second kind of sinkholes are known as Cover Collapse sinkhole. These take place when the bedrock is covered by a deep layer of soil and earth. Once the bedrock begins to get eroded, crack start forming in the rocky areas around it. When this happens, a number of weak points begin to form in the layers of soil and strata above it. Finally, it comes to a point when the weak points become a large hole within the bedrock that cannot support the weight above it. The cover collapse usually happens in a sudden manner and can create large holes in a matter of minutes.

The last kind of sinkholes are known as Cover Subsidence Sinkhole. In this case, the hole is formed over a period of time. The bedrock here is covered by soil and materials which are not well knitted together. Areas that have soil comprising largely of clay or sand often face the occurrence of this hole. Once the bedrock starts to erode, the clay or sand starts permeating through the cracks and settles into the spaces left behind. Over time, this creates a cavity on the surface of the soil and not under it.

Lesson Plan: Here is a great lesson plan on the science of a sinkhole.

Lesson Plan: This is a fun lesson plan where kids can make a sinkhole in a cup.

Lesson Plan: Here is a great lesson plan on how sinkholes form.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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What are sinkholes? Sinkholes are pits in the ground that form in areas where water gathers without external drainage. Sinkholes mainly occur as water drains below ground. It can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.

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A tornado is a tube of violently spinning air that touches the ground. Wind inside the tornado spins fast, but the actual 'circle' of wind around them is huge. This makes tornadoes very dangerous. Tornadoes are especially dangerous to people in cars or mobile homes. About 60 people are killed by tornadoes every year.

The word tornado comes from the Spanish word tornado (past participle of 'to turn', or 'to have turned', which comes from the Latin tonare 'to thunder'.

Tornadoes destroy things. They can tear houses to pieces and often leave people homeless. They are smaller than hurricanes but stronger. Nearly three quarters of the world's tornadoes happen in the United States. However, they can happen anywhere.

They cause a lot of damage to anything in their path. Tornadoes are ranked on the Enhanced Fujita scale, from E F0 to E F5. E F0 for tornados that caused the least damage, and E F5 for the ones that caused the most.

Tornadoes can happen in nearly any part of the world. In the United States, a tornado has happened in all states. The middle part of the United States is nicknamed ' Tornado Alley' for the number of tornadoes there. A tornado can have wind speeds of over 300 miles per hour (480 km/h).

Most tornadoes have wind speeds less than 110 miles per hour (180 km/h), are about 250 feet (80 m) across and travel a few miles before disappearing. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirls, and steam devil; downbursts are frequently confused with tornadoes, though their action is not similar.

A "tornado watch" is given when the weather conditions look like a tornado could form. A 'PDS (Particularly Dangerous Situation)' watch is given when a likely tornado outbreak is to start, many strong tornadoes will form in the area, or an ongoing tornado outbreak is in the works in the area. A " tornado warning" is given if somebody has actually seen a tornado or if a tornado 'signature' (usually the storm has a 'hook' or 'U' echo) has shown up on radar. Tornado emergencies are issued in Special Weather Statements or Tornado Warnings saying that a powerful tornado is about to hit an area with a lot of people in it (especially cities in Tornado Alley), a tornado has been spotted, and the tornado is expected to cause deaths.

Characteristics

Size and shape

Most tornadoes take on the appearance of a narrow funnel, a few hundred meters (yards) across, with a small cloud of debris near the ground. Tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not see them.

Small, relatively weak landspouts may be visible only as a small swirl of dust on the ground. Although the condensation funnel may not extend all the way to the ground, if associated surface winds are greater than 64 km/h (40 mph), the circulation is considered a tornado. A tornado with a nearly cylindrical profile and relatively low height is sometimes referred to as a "stovepipe" tornado. Large tornadoes which appear at least as wide as their cloud-to-ground height can look like large wedges stuck into the ground, and so are known as "wedge tornadoes" or "wedges". A wedge can be so wide that it appears to be a block of dark clouds, wider than the distance from the cloud base to the ground. Even experienced storm observers may not be able to tell the difference between a low-hanging cloud and a wedge tornado from a distance. Many, but not all major tornadoes are wedges.

Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes. These tornadoes are said to be "roping out", or becoming a "rope tornado". When they rope out, the length of their funnel increases, which forces the winds within the funnel to weaken. Multiple-vortex tornadoes can appear as a family of swirls circling a common center, or they may be completely obscured by condensation, dust, and debris, appearing to be a single funnel.

In the United States, tornadoes are around 500 feet (150 m) across on average. However, there is a wide range of tornado sizes. Weak tornadoes, or strong yet dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet or couple meters across. One tornado was reported to have a damage path only 7 feet (2.1 m) long. On the other end of the spectrum, wedge tornadoes can have a damage path a mile (1.6 km) wide or more. A tornado that affected Hallam, Nebraska on May 22, 2004, was up to 2.5 miles (4.0 km) wide at the ground, and a tornado in El Reno, Oklahoma on May 31, 2013, was approximately 2.6 miles (4.2 km) wide, the widest on record.

Track length

In the United States, the average tornado travels on the ground for 5 miles (8.0 km). However, tornadoes are capable of both much shorter and much longer damage paths: one tornado was reported to have a damage path only 7 feet (2.1 m) long, while the record-holding tornado for path length-the Tri-State Tornado, which affected parts of Missouri, Illinois, and Indiana on March 18, 1925-was on the ground continuously for 219 miles (352 km). Many tornadoes which appear to have path lengths of 100 miles (160 km) or longer are composed of a family of tornadoes which have formed in quick succession.

Appearance

Tornadoes can have a wide range of colors, depending on the environment in which they form. Those that form in dry environments can be nearly invisible, marked only by swirling debris at the base of the funnel. Condensation funnels that pick up little or no debris can be gray to white. While traveling over a body of water (as a waterspout), tornadoes can turn white or even blue. Slow-moving funnels, which ingest a considerable amount of debris and dirt, are usually darker, taking on the color of debris. Tornadoes in the Great Plains can turn red because of the reddish tint of the soil, and tornadoes in mountainous areas can travel over snow-covered ground, turning white.

Lighting conditions are a major factor in the appearance of a tornado. A tornado which is "back-lit" (viewed with the sun behind it) appears very dark. The same tornado, viewed with the sun at the observer's back, may appear gray or brilliant white. Tornadoes which occur near the time of sunset can be many different colors, appearing in hues of yellow, orange, and pink.

Dust kicked up by the winds of the parent thunderstorm, heavy rain and hail, and the darkness of night are all factors that can reduce the visibility of tornadoes. Tornadoes occurring in these conditions are especially dangerous, since only weather radar observations, or possibly the sound of an approaching tornado, serve as any warning to those in the storm's path. Most significant tornadoes form under the storm's updraft base, which is rain-free, making them visible. Also, most tornadoes occur in the late afternoon, when the bright sun can penetrate even the thickest clouds.

There is mounting evidence, including Doppler on Wheels mobile radar images and eyewitness accounts, that most tornadoes have a clear, calm center with extremely low pressure, akin to the eye of tropical cyclones. Lightning is said to be the source of illumination for those who claim to have seen the interior of a tornado.

Tornadoes normally rotate cyclonically (when viewed from above, this is counterclockwise in the northern hemisphere and clockwise in the southern).

Sound and seismology

Various sounds of tornadoes have been reported. They include a freight train, rushing rapids or waterfall, a nearby jet engine, or combinations of these. Many tornadoes are not audible from much distance; the nature of and the propagation distance of the audible sound depends on atmospheric conditions and topography.

Since many tornadoes are audible only when very near, sound is not to be thought of as a reliable warning signal for a tornado.

How they form

Tornadoes often develop from a class of thunderstorms known as supercells. Supercells contain mesocyclones, an area of organized rotation a few kilometers/miles up in the atmosphere, usually 1.6-9.7 km (1-6 miles) across. Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells. In addition to tornadoes, very heavy rain, frequent lightning, strong wind gusts, and hail are common in such storms.

Most tornadoes from supercells follow a recognizable life cycle which begins when increasing rainfall drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the supercell's rotating mesocyclone towards the ground with it.

As the mesocyclone lowers below the cloud base, it begins to take in cool, moist air from the downdraft region of the storm. The convergence of warm air in the updraft and cool air causes a rotating wall cloud to form. The RFD also focuses the mesocyclone's base, causing it to draw air from a smaller and smaller area on the ground. As the updraft intensifies, it creates an area of low pressure at the surface. This pulls the focused mesocyclone down, in the form of a visible condensation funnel. As the funnel descends, the RFD also reaches the ground, fanning outward and creating a gust front that can cause severe damage a considerable distance from the tornado. Usually, the funnel cloud begins causing damage on the ground (becoming a tornado) within a few minutes of the RFD reaching the ground.

Initially, the tornado has a good source of warm, moist air flowing inward to power it, and it grows until it reaches the "mature stage". This can last from a few minutes to more than an hour, and during that time a tornado often causes the most damage, and in rare cases can be more than 1.6 km (1 mile) across. The low pressured atmosphere at the base of the tornado is essential to the endurance of the system. Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which previously fed the tornado. The flow inside the funnel of the tornado is downward, supplying water vapor from the cloud above. This is contrary to the upward flow inside hurricanes, supplying water vapor from the warm ocean below.

Dissipation

As the RFD completely wraps around and chokes off the tornado's air supply, the vortex begins to weaken, becoming thin and rope-like. This is the "dissipating stage", often lasting no more than a few minutes, after which the tornado ends. During this stage, the shape of the tornado becomes highly influenced by the winds of the parent storm, and can be blown into fantastic patterns. Even though the tornado is dissipating, it is still capable of causing damage. The storm is contracting into a rope-like tube and, due to conservation of angular momentum, winds can increase at this point.

Although this is a widely accepted theory for how most tornadoes form, live, and die, it does not explain the formation of smaller tornadoes, such as landspouts, long-lived tornadoes, or tornadoes with multiple vortices. These each have different mechanisms which influence their development-however, most tornadoes follow a pattern similar to this one.

Multiple vortex

A multiple-vortex tornado is a type of tornado in which two or more columns of spinning air rotate about their own axes and at the same time revolve around a common center. A multi-vortex structure can occur in almost any circulation, but is very often observed in intense tornadoes. These vortices often create small areas of heavier damage along the main tornado path. This is a phenomenon that is distinct from a satellite tornado, which is a smaller tornado that forms very near a large, strong tornado contained within the same mesocyclone. The satellite tornado may appear to " orbit" the larger tornado (hence the name), giving the appearance of one, large multi-vortex tornado. However, a satellite tornado is a distinct circulation, and is much smaller than the main funnel.

Waterspout

A waterspout is defined by the National Weather Service as a tornado over water. However, researchers typically distinguish "fair weather" waterspouts from tornadic (i.e. associated with a mesocyclone) waterspouts. Fair weather waterspouts are less severe but far more common, and are similar to dust devils and landspouts. They form at the bases of cumulus congestus clouds over tropical and subtropical waters. They have relatively weak winds, smooth laminar walls, and typically travel very slowly. They occur most commonly in the Florida Keys and in the northern Adriatic Sea. In contrast, tornadic waterspouts are stronger tornadoes over water. They form over water similarly to mesocyclonic tornadoes, or are stronger tornadoes which cross over water. Since they form from severe thunderstorms and can be far more intense, faster, and longer-lived than fair weather waterspouts, they are more dangerous. In official tornado statistics, waterspouts are generally not counted unless they affect land, though some European weather agencies count waterspouts and tornadoes together.

A landspout, or dust-tube tornado, is a tornado not associated with a mesocyclone. The name stems from their characterization as a "fair weather waterspout on land". Waterspouts and landspouts share many defining characteristics, including relative weakness, short lifespan, and a small, smooth condensation funnel that often does not reach the surface. Landspouts also create a distinctively laminar cloud of dust when they make contact with the ground, due to their differing mechanics from true mesoform tornadoes. Though usually weaker than classic tornadoes, they can produce strong winds which could cause serious damage.

Intensity and damage

The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. The Enhanced Fujita (EF) Scale was an update to the older Fujita scale. The EF Scale was designed so that a tornado rated on the Fujita scale would receive the same numerical rating, and was implemented starting in the United States in 2007. An EF0 tornado will probably damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler weather radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.

Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track tornadoes tend to be stronger. In the case of violent tornadoes, only a small portion of the path is of violent intensity, most of the higher intensity from subvortices.

In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes.

Outside Tornado Alley, and North America in general, violent tornadoes are extremely rare. This is apparently mostly due to the lesser number of tornadoes overall, as research shows that tornado intensity distributions are fairly similar worldwide. A few significant tornadoes occur annually in Europe, Asia, southern Africa, and southeastern South America.

Main page: Convective storm detection

Rigorous attempts to warn of tornadoes began in the United States in the mid-20th century. Before the 1950s, the only method of detecting a tornado was by someone seeing it on the ground. Often, news of a tornado would reach a local weather office after the storm. However, with the advent of weather radar, areas near a local office could get advance warning of severe weather. The first public tornado warnings were issued in 1950 and the first tornado watches and convective outlooks came about in 1952. In 1953, it was confirmed that hook echoes were associated with tornadoes. By recognizing these radar signatures, meteorologists could detect thunderstorms probably producing tornadoes from several miles away.

Today most developed countries have a network of weather radars, which serves as the primary method of detecting hook signatures that are likely associated with tornadoes. In the United States and a few other countries, Doppler weather radar stations are used. These devices measure the velocity and radial direction (towards or away from the radar) of the winds within a storm, and so can spot evidence of rotation in storms from over 160 km (100 miles) away. When storms are distant from a radar, only areas high within the storm are observed and the important areas below are not sampled. Data resolution also decreases with distance from the radar. Some meteorological situations leading to tornadogenesis are not readily detectable by radar and tornado development may occasionally take place more quickly than radar can complete a scan and send the batch of data. Doppler radar systems can detect mesocyclones within a supercell thunderstorm. This allows meteorologists to predict tornado formations throughout thunderstorms.

Storm spotting

Spotters usually are trained by the NWS on behalf of their respective organizations, and report to them. The organizations activate public warning systems such as sirens and the Emergency Alert System (EAS), and they forward the report to the NWS. There are more than 230,000 trained Skywarn weather spotters across the United States.

In Canada, a similar network of volunteer weather watchers, called Canwarn, helps spot severe weather, with more than 1,000 volunteers. In Europe, several nations are organizing spotter networks under the auspices of Skywarn Europe and the Tornado and Storm Research Organisation (TORRO) has maintained a network of spotters in the United Kingdom since 1974.

Storm spotters are required because radar systems such as NEXRAD detect signatures that suggest the presence of tornadoes, rather than tornadoes as such. Radar may give a warning before there is any visual evidence of a tornado or an imminent one, but ground truth from an observer can give definitive information. The spotter's ability to see what radar cannot is especially important as distance from the radar site increases, because the radar beam becomes progressively higher in altitude further away from the radar, chiefly due to curvature of Earth, and the beam also spreads out.

Visual evidence

Storm spotters are trained to discern whether or not a storm seen from a distance is a supercell. They typically look to its rear, the main region of updraft and inflow. Under that updraft is a rain-free base, and the next step of tornadogenesis is the formation of a rotating wall cloud. The vast majority of intense tornadoes occur with a wall cloud on the backside of a supercell.

Evidence of a supercell is based on the storm's shape and structure, and cloud tower features such as a hard and vigorous updraft tower, a persistent, large overshooting top, a hard anvil (especially when backsheared against strong upper level winds), and a corkscrew look or striations. Under the storm and closer to where most tornadoes are found, evidence of a supercell and the likelihood of a tornado includes inflow bands (particularly when curved) such as a "beaver tail", and other clues such as strength of inflow, warmth and moistness of inflow air, how outflow- or inflow-dominant a storm appears, and how far is the front flank precipitation core from the wall cloud. Tornadogenesis is most likely at the interface of the updraft and rear flank downdraft, and requires a balance between the outflow and inflow.

Only wall clouds that rotate spawn tornadoes, and they usually precede the tornado between five and thirty minutes. Rotating wall clouds may be a visual manifestation of a low-level mesocyclone. Barring a low-level boundary, tornadogenesis is highly unlikely unless a rear flank downdraft occurs, which is usually visibly evidenced by evaporation of cloud adjacent to a corner of a wall cloud. A tornado often occurs as this happens or shortly afterwards; first, a funnel cloud dips and in nearly all cases by the time it reaches halfway down, a surface swirl has already developed, signifying a tornado is on the ground before condensation connects the surface circulation to the storm. Tornadoes may also develop without wall clouds, under flanking lines and on the leading edge. Spotters watch all areas of a storm, and the cloud base and surface.

Myths and misconceptions

It is often thought that opening windows will lessen the damage caused by a tornado. While there is a big drop in atmospheric pressure inside a strong tornado, it is unlikely that the pressure drop would be enough to cause the house to explode. Opening windows may actually increase the tornado's damage. A violent tornado can destroy a house whether its windows are open or closed. Another common misconception is that highway overpasses provide adequate shelter from tornadoes. Due to the Venturi effect, tornadic winds are stronger in the small space of an overpass. In the 1999 Oklahoma tornado outbreak of May 3, 1999, three highway overpasses were directly hit by tornadoes. At each of the three places there was a death, along with many life-threatening injuries. By comparison, during the same tornado outbreak, more than 2000 homes were completely destroyed, with another 7000 damaged, and yet only a few dozen people died in their homes.

There are areas which people believe to be safe from tornadoes, whether by being in a city, near a major river, hill, or mountain, or even protected by supernatural forces. Tornadoes have been known to cross major rivers, climb mountains, hit valleys, and have damaged several city centers. As a general rule, no area is safe from tornadoes, though some areas are more likely to be hit than others.

Safety tips

To keep safe in a tornado, here are some tips you can follow:

Go to the lowest floor of the building. Stay close to the center of the building and away from windows, for example, a bathroom with no windows and get into the bathtub.

Find a piece of strong furniture or a mattress to go under or hide in a closet and wait until it is over.

If you are in a school, do not go to the gymnasium or any other place that has a high ceiling. Squat near the wall, placing your hands on the back of your head.

If you cannot find shelter, find the lowest, most protected ground and cover your head with your hands.

Do not drive in tornadoes. If you are in your car, position your head above the steering wheel, and cover yourself up.

Do not seek shelter underneath an underpass or a bridge, as winds can send debris in your path.

Related pages

In Spanish: Tornado para niños

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Tornado Facts For Kids

Enjoy our fun tornado facts for kids! Learn what tornadoes are, how fast they spin, how far they can travel, where most tornadoes occur, the difference between an F0 tornado and an F5 tornado, what a waterspout is and much more.

Read on to check out our wide range of information on twisters.

A tornado is a rapidly spinning tube of air that touches both the ground and a cloud above.

Tornadoes are sometimes called twisters.

Not all tornadoes are visible but their high wind speeds and rapid rotation often form a visible funnel of condensed water.

The Fujita Scale is a common way of measuring the strength of tornadoes. The scale ranges from F0 tornadoes that cause minimal damage through to F5 tornadoes which cause massive damage.

Most tornadoes have wind speeds less than 100 miles per hour (161 kilometres per hour).

Extreme tornadoes can reach wind speeds of over 300 miles per hour (483 kilometres per hour).

Most tornadoes travel a few miles before exhausting themselves.

Extreme tornadoes can travel much further, sometimes over 100 miles (161kilometres).

The Tri-State Tornado that travelled through parts of Missouri, Illinois and Indiana in 1925 left a path of destruction over 219 miles (352 kilometres) long.

The Tri-State Tornado was the deadliest tornado in US history, killing 695 people.

The USA averages around 1200 tornadoes every year, more than any other country.

The majority of these tornadoes occur in a geographically unique area nicknamed 'Tornado Alley'.

US States most often hit by tornadoes include Texas, Kansas, Oklahoma and Florida.

In 1989 the deadliest tornado ever recorded in the world killed around 1300 people in Bangladesh.

In the southern hemisphere tornadoes usually rotate in a clockwise direction.

In the northern hemisphere tornadoes usually rotate in a counterclockwise direction.

A tornado that occurs over water is often called a waterspout.

Weather radars are used to detect tornadoes and give advanced warning.

Basements and other underground areas are the safest places to seek refuge during a tornado. It is also a good idea to stay away from windows.

Make a tornado in a bottle or watch some amazing tornado video footage.

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Fun Tornado Facts for Kids - Interesting Information about Twisters

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Tornado Facts For Kids Enjoy our fun tornado facts for kids! Learn what tornadoes are, how fast they spin, how far they can travel, where most tornadoes occur, the difference between an F0 tornado and an F5 tornado, what a waterspout is and much more.

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A tornado is a type of storm in which powerful rotating winds form a column, which reaches from a cloud down toward the ground. The winds of a tornado are the strongest on...

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A dark greenish tinge covers the sky, and black storm clouds threaten above. The wind roars loudly while cats hide under couches and dogs start howling. A tornado is forming.

Also known as twisters, tornadoes are violently spinning, funnel-shaped columns of air that stretch from the dark thunderclouds they form in all the way to the ground. The wind from a tornado can top 250 miles an hour-that's faster than a race car! These extreme gusts can rip apart buildings, destroy bridges, flip trains, and send cars flying. They can even tear the bark off trees and suck all the water from a riverbed.

Tornadoes occur all over the planet, but the United States leads the world in the strength and number of storms: About a thousand twisters touch down every year. ( Argentina and Bangladesh are next.) As part of larger U.S. storm systems, they cause about 80 deaths a year and close to $1 billion in damage.

How tornadoes develop

Thunderstorms form when cold, dry air is pushed over warm, humid air. When that warm air rises through the colder air, it causes an updraft, or a change in wind direction.

If winds from the thunderstorm vary greatly in speed or direction, the updraft will begin to rotate. As the rotating updraft draws in more warm air from the moving thunderstorm, its rotation speed increases, and a funnel cloud begins to form. As the twister gains strength, the funnel becomes longer. (The funnel becomes more visible as more dirt and debris is caught in its rotation.) It's most dangerous when it touches the ground.

The most violent tornadoes come from supercells-the name scientists give to large thunderstorms with winds already in rotation. About one in a thousand thunderstorms becomes a supercell, and one in five or six supercells creates a tornado.

For all their power, the average tornado lasts only about 10 minutes, though some can rage for over an hour. Twisters usually die when they move over colder ground or when the clouds above it start to break up.

The Tri-State Tornado of 1925 holds the record for time and distance of a tornado. Named for the three states it hit- Missouri, Illinois, and Indiana -the tornado took three and a half hours to tear through 219 miles.

Where and when tornadoes form

Although tornadoes have been spotted in every U.S. state, many form in a region called Tornado Alley. This zone in the Midwest extends from Texas to Ohio and includes Iowa, Kansas, South Dakota, Oklahoma, and Nebraska.

These states are in the path of warm, moist air traveling from the Gulf of Mexico as well as cool air blowing from the Rocky Mountains. When the warm and cool airstreams meet, tornadoes are likely to form.

Though the storms can happen at any time of the year, tornado season in Texas, Oklahoma, and Kansas occurs in May through early June. In North and South Dakota, Nebraska, Iowa, and Minnesota, tornadoes are more likely to form in June or July.

Tracking tornadoes

During thunderstorms, meteorologists use weather satellites, weather balloons, and buoys to gather data like wind speed and temperature. Then they analyze that data with supercomputers. This helps scientists pinpoint where and when a twister might form, as well as how strong or long-lasting it might be.

If weather conditions are right for a tornado to form, experts issue a tornado watch for a region, like a county or large part of a state. This doesn't mean that a tornado is on the way. But it could be-meteorologists issue the watch so people can be prepared.

When a tornado is spotted or picked up on weather radar, scientists issue a tornado warning for a smaller area, like a town or part of a city. People there are urged to take cover.

Some experts actually drive into areas where storms are forming! Vehicles tricked out with special science equipment measure things like temperature, humidity, and air pressure that's submitted to meteorologists at weather service headquarters. But the information that these "tornado chasers" gather also helps scientists better understand the science of tornados.

Thanks to these tools, meteorologists are now able to quickly predict when and where a tornado will form, giving people in a twister's path more time to seek shelter. For instance, in the 1980s, people only had about a five-minute warning before a tornado hit; by the late 2000s, the warning time grew to 13 minutes.

How to survive a tornado
Before a tornado
* Listen to weather reports for tornado warnings.
* Close all the windows.
* Prepare a safe room. This can be your basement or the lowest room in the center of your house or apartment building, away from outer walls and windows. Window-free closets and bathrooms work well, too.
* Fill the safe room with blankets, pillows, sleeping bags, and your family emergency kit (water, food, flashlight, and radio).
* Have an emergency safety plan. If you live in a trailer or mobile home, make sure you know where to go to evacuate.
During a tornado
* Stay inside-never attempt to watch or chase a tornado.
* Do not go near windows. It's not the tornado itself that causes most injuries; it's the flying debris-or the windows they crash through-that cause most injuries.
* Cover yourself with the pillows, blankets, and sleeping bags. If there's a sturdy piece of furniture, like a table, crawl under it.
* Cover your head and neck with your arms.
* If you're caught outside and can't find shelter, look for a ditch, gulley, or just a flat piece of ground away from trees and cars. Lie down as flat as you can and cover your head and neck with your arms. (Do not try this under a bridge or overpass.)
After a tornado
* Do not leave your shelter until local authorities give the OK. Follow their instructions.
* If you go outside, watch where you step-dangerous debris can be anywhere.
* Continue to monitor tornado reports. Sometimes more than one can whip up in the same place.
Learn more about tornadoes at National Geographic.
Tornado safety tips from the Nat Geo Kids book Extreme Weather by Thomas Kostigen and How to Survive Anything by Rachel Buchholz

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Find out what causes these deadly twisters-and how to stay safe.

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Tornadoes

What is a tornado?
A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to 300 mph. They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees. Damage paths can be in excess of one mile wide to 50 miles long. In an average year, 1000 tornadoes are reported nationwide.

How do tornadoes form?

Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.

Click Here to learn more about tornadoes from NOAA.

What are some other factors for tornadoes to form?
Several conditions are required for the development of tornadoes and the thunderstorm clouds with which most tornadoes are associated. Abundant low level moisture is necessary to contribute to the development of a thunderstorm, and a "trigger" (perhaps a cold front or other low level zone of converging winds) is needed to lift the moist air aloft. Once the air begins to rise and becomes saturated, it will continue rising to great heights to produce a thunderstorm cloud, if the atmosphere is unstable. An unstable atmosphere is one where the temperature decreases rapidly with height. Atmospheric instability can also occur when dry air overlays moist air near the earth's surface. Finally, tornadoes usually form in areas where winds at all levels of the atmosphere are not only strong, but also turn with height in a clockwise or veering direction.

What do tornadoes look like?
Tornadoes can appear as a traditional funnel shape, or in a slender rope-like form. Some have a churning, smoky look to them, and other contain "multiple vortices", which are small, individual tornadoes rotating around a common center. Even others may be nearly invisible, with only swirling dust or debris at ground levels as the only indication of the tornado's presence.

What is a funnel cloud? A funnel cloud is a rotating cone-shaped column of air extending downward from the base of a thunderstorm, but not touching the ground. When it reaches the ground it is called a tornado.

It is not fully understood about how exactly tornadoes form, grow and die. Tornado researchers are still trying to solve the tornado puzzle, but for every piece that seems to fit they often uncover new pieces that need to be studied. How do tornadoes stop?

A supercell thunderstorm is a long-lived thunderstorm whose updrafts and downdrafts are in near balance. These storms have the greatest tendency to produce tornadoes that stay on the ground for long periods of time. Supercell thunderstorms can produce violent tornadoes with winds exceeding 200 mph.
What is a supercell thunderstorm?

A mesocyclone is a rotating vortex of air within a supercell thunderstorm. Mesocyclones do not always produce tornadoes.
What is a mesocyclone?

A wall cloud is an abrupt lowering of a rain-free cumulonimbus base into a low-hanging accessory cloud. A wall cloud is usually situated in the southwest portion of the storm. A rotating wall cloud usually develops before tornadoes or funnel clouds. What is a microburst?
A microburst is a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale. Although microbursts are not as widely recognized as tornadoes, they can cause comparable, and in some cases, worse damage than some tornadoes produce. In fact, wind speeds as high as 150 mph are possible in extreme microburst cases.
What is a wall cloud?

A waterspout is just a weak tornado that forms over water. They are most common along the Gulf Coast. Waterspouts can sometimes move inland, becoming tornadoes causing damage and injuries.

What is a waterspout?

What is hail?
Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall. If the smaller hailstones get caught in the updraft again, they will get more water on them and get lifted higher in the sky and get bigger. Once they get lifted again, they freeze and fall. This happens over and over again until the hailstone is too heavy and then falls to the ground.

What is the largest hailstone recorded in the United States?
According to the National Weather Service, the largest hailstone is 8 inches in diameter and weights approximately 2 pounds. It fell in Vivian, South Dakota on July 23, 2010.
A gustnado is a short-lived, relatively weak whirlwind that forms along a gust front. A gust front is the surge of very gusty winds at the leading edge of a thunderstorm's outflow of air. Gustnadoes are not tornadoes. They do not connect with any cloud-base rotation. But because gustnadoes often have a spinning dust cloud at ground level, they are sometimes wrongly reported as tornadoes. Gustnadoes can do minor damage.

What is a gustnado?
A landspout is a very weak tornado that is not associated with a wall cloud or a mesocyclone. It is the land equivalent of a waterspout.

What is a landspout?
A dust devil generally forms in the hot sun during the late morning or early afternoon hours. These are mostly harmless whirlwinds and are triggered by light desert breezes that create a swirling plume of dust with speeds rarely over 70 mph. These differ from tornadoes in that they are not associated with a thunderstorm (or any cloud) and are usually very weak.

What is a dust devil? Tornadoes can happen at any time of the year and at any time of the day. In the southern states, peak tornado season is from March through May. Peak times for tornadoes in the northern states are during the summer. A few southern states have a second peak time for tornado outbreaks in the fall. Tornadoes are most likely to occur between 3 p.m. and 9 p.m.

The geography of the central part of the United States, known as the Great Plains, is suited to bring all of the ingredients together to forms tornadoes. More than 500 tornadoes typically occur in this area every year and is why it is commonly known as "Tornado Alley". Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Iowa, Missouri, Arkansas and Louisiana all make up Tornado Alley. When are tornadoes most likely to occur?

Where are tornadoes most likely to occur?

Know the Lingo

TORNADO WATCH - Tornadoes are possible in your area. Stay tuned to the radio or television news.
TORNADO WARNING - A tornado is either on the ground or has been detected by Doppler radar. Seek shelter immediately!

Click Here to see if there are any active warnings in your area.

Know the Facts
Tornadoes can occur at any time of the year. nd winds less than 110 mph.

No terrain is safe from tornadoes.

Never open windows in severe weather situations. This allows damaging wind and debris to enter the structure.

69% of all tornadoes are labeled "weak tornadoes" meaning they have a lifetime of 1-10+ minutes a

SCALE

WIND SPEED

POSSIBLE DAMAGE

Enhanced,
Operational
Fujita Scale

29% of all tornadoes are labeled "strong tornadoes" meaning they last 20 minutes or longer and winds reach 110-205 mph.
2% of all tornadoes are labeled "violent tornadoes" and can last over an hour.

Fujita Scale of Tornado Intensity

Tornado Safety Tips
BEFORE A TORNADO: Have a disaster plan. Make sure everyone knows where to go in case a tornado threatens. Make sure you know which county or parish you live in. Prepare a kit with emergency food for your home. Have enough food and water for at least 3 days.

AFTER A TORNADO: Stay indoors until it is safe to come out. Check for injured or trapped people, without putting yourself in danger. Watch out for downed power lines. Use a flashlight to inspect your home. Tornado Activities

Lesson Plan: Here are some great lesson plans on learning about tornado safety. Note: This is a PDF file, so you need to have Adobe Acrobat Reader. DURING A TORNADO: Go to a basement. If you do not have a basement, go to an interior room without windows on the lowest floor such as a bathroom or closet. If you can, get under a sturdy piece of furniture, like a table. If you live in a mobile home get out. They offer little protection against tornadoes. Get out of automobiles. Do not try to outrun a tornado in your car, leave it immediately. If you're outside, go to a ditch or low lying area and lie flat in it. Stay away from fallen power lines and stay out of damaged areas.
Tornado Experiment: Here is a great experiment that allows the kids to make a tornado in a bottle.
IF YOU'RE AT SCHOOL DURING A TORNADO: Every school should have a disaster plan and have frequent drills. Basements offer the best protection. Schools without basements should use interior rooms and hallways on the lowest floor away from windows. Crouch down on your knees and protect your head with your arms.
Tornado Experiment: Here is a great experiment that allows the kids to make a tornado in a jar.
Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!
Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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Tornadoes are one of the most violent and powerful types of weather. They consist of a very fast rotating column of air that usually forms a funnel shape. They can be very dangerous as their high speed winds can break apart buildings, knock down trees, and even toss cars into the air.

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Kids learn about tornadoes including how they form, characteristics, types including supercell and waterspout, categories, and fun facts.

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Winter storms or snowstorms happen when warm, wet air meets with cold air. The warm, wet air mass and the cold air mass can each be 1000 km or more in diameter. Snowstorms affecting Northeastern United States often get their moisture from air moving north from the Gulf of Mexico and cold air from air masses coming down from the Arctic. In the Northwest United States warm, wet air from the Pacific Ocean cools when it is pushed upward by the mountains. Many different things can affect the direction of movement, moisture content and temperature of air masses. All of these differences affect the type and severity of the snowstorm.

Winter storms and blizzards can make several feet of snow that blow into big drifts. Sometimes the drifts can be over ten feet tall. They could even cover a house.

Lots of popular winter storms are part of North America's history. In 1846 the Donner Party traveled away by covered wagons from Illinois headed for Sutter's Fort near Sacramento, California. As an answer of bad decisions and slow going, they tried to go across the big Sierra Nevada Mountains in the late October. Usually, California is still warm at that time of the year. As the party crossed the Sierra Nevada Mountains, they did not see any snow and was not worried. However, after they left, a huge snowstorm hit. The party was forced to camp near Truckee, California. The snow was so deep that the wagon wheels became stuck, so they could not move anyplace. They tried to wait the storm out, but when one blizzard ended, another began immediately before they had time to escape. Their food became short, so some of the people decided to hike out and find help rather than to starve to death. Most of them died in the freezing weather, and many of those who stayed behind in the camp survived. Of the 87 people who started in Illinois, only 47 lived.

Images for kids

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Winter storms or snowstorms happen when warm, wet air meets with cold air. The warm, wet air mass and the cold air mass can each be 1000 km or more in diameter. Snowstorms affecting Northeastern United States often get their moisture from air moving north from the Gulf of Mexico and cold air from air masses coming down from the Arctic.

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By definition, a blizzard is an extended, severe snowstorm. In order to qualify as a blizzard, winds have to be at least 35mph and rage for a longer period of time-at least three hours or more. The amount of snowfall has little to do with a storm qualifying as a snowstorm, but rather the intensity of the wind and length of time. There are two other classifications for blizzards:

--Severe blizzard: winds over 45mph, temperatures at 10 Fahrenheit or lower, near zero visibility.

--Ground blizzard: no falling snow, snow from the ground is blown by the strong winds.

A nor'easter gets it's name from the direction of the oncoming winds. This occurs on the Atlantic side of Canada and East Coast of the USA. These storms can start as far south as the Gulf of Mexico or the North Atlantic Ocean. However, the most common usage of the name is in the coastal regions of Atlantic Canada and New England. These storms are similar to a hurricane. One of the deadliest blizzards in the USA-the Great Blizzard of 1888-was a nor'easter, killing 400 people after dumping 40-50 inches of snow.

Blizzards are usually formed when the jet stream pitches very far south. This allows the cold air that comes from the north to collide with warm air coming from the south. This creates a strong storm system, usually developing on the northwest side of such storm systems.

Any area which is mostly flat is susceptible to blizzards, though there are some areas in the US, Australia, and the UK that suffer from blizzards more than others. However, the deadliest blizzard in recorded history occurred in Iran in 1972.

Blizzards are one of nature's deadlier storms, as the conditions make travel and movement hazardous. Snowstorms disrupt traffic, but blizzards make any kind of travel nearly impossible. Almost every blizzard results in at least a few deaths, with some of the bigger ones resulting in hundreds of people dying.

Visibility is drastically reduced, in some cases to as little as 3 meters or what is called zero visibility. In a ground blizzard, though no new snow is falling, the snow already on the ground is whipped up and around by the winds to where visibility is also close to zero.

Travel under these conditions is close to impossible. Cars have to come to a complete standstill as they can drive off the road. Because blizzards rage for so long, people can get trapped in their cars, freezing to death as they wait for it to clear. Once the storm is over, cars are often buried under mounds of snow, making it difficult for rescue teams to find them. Hypothermia sets in as people trapped outdoors try to find shelter and warmth.

Blizzards have been known to come suddenly and while it is possible to be warned in advance, it's not always possible to be entirely prepared for the intensity of the blizzard. Clearing roads is not possible until after the blizzard has passed and then takes a long time due to the intensity of the build up. The aftermath of the blizzard can be almost as dangerous as the storm itself, as people trapped inside vehicles, unheated buildings, or outdoors take longer to be found and brought to warmth and safety.

Though not as common as snowstorms, tornadoes, or even hurricanes, blizzards are deadly every time they hit. Not all blizzards are mentioned here, not even all of the most severe. This is just a sample of the havoc that blizzards can wreak.

--The white winter of 1880-1881 is one of the earliest blizzards mentioned in history books. This is considered the worst winter in US history. Because the first blizzard hit in October, before most farmers had the opportunity to bring in their crops. One after the other the blizzards continued to hit, making travel impossible, even by train. People were at the brink of starvation and train services stopped completely by January 1880 as no matter how often they cleared the tracks, another storm would come and cover them again. The snow never thawed and on February 2, 1881 a nine day blizzard hit again. By then, towns and farmers had to tunnel through the snow to get to livestock, wood for heating, and supplies. Once the snow started melting, huge areas were flooded, washing away huge areas around the Missouri river. The town of Yankton, currently South Dakota, was nearly completely washed away by the overflowing river.

--The Iran Blizzard of 1972 is the deadliest recorded blizzard. Starting on February 3, until February 9, more than 10 feet of snow fell, the worst areas in Southern Iran getting up to 26 feet of snow. Whole villages died, one being completely buried beneath the snow. Approximately 4000 people died.

--The Armistice Day Blizzard in 1947 came somewhat unexpected, resulting in a lot of deaths. On the morning of the blizzard, the weather was warm, resulting in many hunters going out to take advantage of ideal conditions. Within a few hours, the blizzard hit, raging through the night and into the next day. 145 deaths were reported as a result of the 1,000 mile wide storm. Many hunters were not dressed warmly enough to withstand the wind and snow. Many were stranded on islands in the Mississippi, or drowned trying to get back to land.

--The Schoolhouse Blizzard in 1888 is different from the nor'easter and in some ways more heart breaking. Because the day started out relatively fair, people went about their lives, with children going to school and adults going to work. The storm hit early in the day, leaving thousands stranded; mostly children in their one-room schoolhouses. 235 people died; including children.

Although meteorologists are now able to more accurately predict blizzards, the storms still have the ability to cripple whole cities at a time, and deaths are almost always inevitable. Over the years, rescue missions during and after blizzards are becoming better and preparedness goes a long way towards preventing large amounts of casualties. It has also become considerably easier to notify people of oncoming storms, with more reliable predictions and getting the word out quickly and effectively.

Countries which are not used to large amounts of snow, extreme cold, and long periods of strong winds tend to have a harder time coping when the storms hit. Regardless of where the blizzards hit, there is never a way to be completely prepared. There is always a chance of power outages, communications systems breaking down, people going for long periods with little or no heat, and getting trapped outdoors or in a vehicle. During winter months, people are advised to pay close attention to weather warning coming over the radio or TV. There are weather websites set up to help people prepare for blizzards and post warnings when a snowstorm is being upgraded to a blizzard.

Blizzard Related Articles

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By definition, a blizzard is an extended, severe snowstorm. In order to qualify as a blizzard, winds have to be at least 35mph and rage for a longer period of time-at least three hours or more. The amount of snowfall has little to do with a storm qualifying as a snowstorm, but rather the intensity of the wind and length of time.

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Nor'easters can occur in the eastern United States any time between October and April, when moisture and cold air are plentiful. A Nor'easter is named for the winds that blow in from the northeast and drive the storm up the east coast along the Gulf Stream, a band of warm water that lies off the Atlantic coast. They are known for dumping heavy amounts of rain and snow, producing hurricane-force winds, and creating high surfs that cause severe beach erosion and coastal flooding. Winter Storms

How do winter storms form?
Winter storms derive their energy from the clash of two air masses of different temperatures and moisture levels. Winter storms usually form when an air mass of cold, dry, Canadian air moves south and interacts with a warm, moist air mass moving north from the Gulf of Mexico. The point where these two air masses meet is called a front. If cold air advances and pushes away the warm air, it forms a cold front. When warm air advances, it rides up over the denser, cold air mass to form a warm front. If neither air mass advances, it forms a stationary front.

What are snowflakes?
Snowflakes are made of ice crystals. Each snowflake is six-sided and made of as many as 200 ice crystals. Snowflakes form in clouds where the temperature is below freezing. The ice crystals form around tiny bits of dirt that has been carried up into the atmosphere by the wind. As the snow crystals grow, they become heavier and fall toward the ground. Why is snow white?
Bright snow blinds us with its gleaming white color because it reflects beams of white light. Instead of absorbing light, snow's complex structure prevents the light from shining through its lattice formation. A beam of white sunlight entering a snow bank is so quickly scattered by a zillion ice crystals and air pockets that most of the light comes bouncing right back out of the snow bank. What little sunlight is absorbed by snow is absorbed equally over the wavelengths of visible light thus giving snow its white appearance. So while many natural objects get their blue, red, and yellow colors from absorbing light, snow is stuck with its white color because it reflects light.

What is thundersnow? How is snow formed?
Snow is commonly formed when water vapor undergoes deposition, which is when water vapor changes directly to ice without first becoming a liquid, high in the atmosphere at a temperature of less than 32°F and then falls to the ground. What is sleet?
Sleet is just rain drops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists.
What is an ice storm?
An ice storm is a type of winter storm caused by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch of ice on exposed surfaces.
What is freezing rain?
Freezing rain is just rain that falls onto a surface with a temperature below freezing. This causes it to freeze to surfaces, such as trees, cars, and roads, forming a coating or glaze of ice. Even small accumulations of ice can cause a significant hazard. How do ice storms form?
Ice storms form when a layer of warm air is between two layers of cold air. Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground. This creates freezing rain or a glaze of ice.

What is frost? What is a frost quake?
Frost is white ice crystals that form on a surface, like the ground or leaves of a plant. Frost is created when the air temperature drops below freezing and the water vapor in the air freezes into ice crystals.

How is lake-effect snow formed?
As the cold air flows over the warm lake water, the relatively warm water heats the air's bottom layer as lake moisture evaporates into the cold air. Since warm air is lighter or less dense than cold air, the heated air rises and begins to cool. As the air cools, the moisture that evaporated into it condenses and forms clouds and snow begins falling from the cloud if the air is humid enough. (Graphic Credit: USA TODAY.) What is a Nor'easter?

What is Wind Chill? What is an Alberta Clipper? Click Here to calculate the Wind Chill.
An Alberta clipper is an area of low pressure that generally forms over Alberta, Canada, east of the Rocky Mountains. They develop east of the Rockies because air flowing eastward over the mountains creates favorable conditions. Once an Alberta Clipper forms it usually moves very rapidly to the southeast across the USA's northern Plains and then to the east off the mid-Atlantic Coast. Clippers usually cause only light precipitation with very few producing major snowstorms. However, if conditions are favorable, some Alberta clippers can rapidly intensify off the East Coast once the storm taps the relatively warm moist air over the Atlantic Ocean. The storms that rapidly intensify sometimes spread heavy snow over New England and southeastern Canada. Generally, the main weather features associated with Alberta clippers are some light snow and a reinforcement of cold air over the USA.
What is frostbite? How do blizzards form?

A blizzard is a long-lasting snowstorm with very strong winds and intense snowfall. You need three things to have a blizzard; cold air at the surface, lots of moisture, and lift. Warm air must rise over cold air.
What is an avalanche?
An avalanche is a moving mass of snow that may contain ice, soil, rocks, and uprooted trees. The height of a mountain, the steepness of its slope, and the type of snow lying on it all help determine the likelihood of an avalanche. Avalanches begin when an unstable mass of snow breaks away from a mountainside and moves downhill. The growing river of snow picks up speed as it rushes down the mountain. Avalanches have been known to reach speeds of 245 miles an hour (394 kilometers per hour)—about four times as fast as the speediest downhill skier.
Click Here to learn more about Avalanche Saftey.
Know the Lingo
WINTER WEATHER ADVISORIES - Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.

Thundersnow is when thunder and lighting occur during a snowstorm. This occurs most often in late winter or early spring. To get thundersnow, you need a mass of cold air on top of warm air, plus moist air closer to the ground. Thundersnow starts out like a summer thunderstorm. The sun heats the ground and pushes masses of warm, moist air upward, creating unstable air columns. As it rises, the moisture condenses to form clouds, which are jostled by internal turbulence. The "tricky part" for making thundersnow is creating that atmospheric instability in the wintertime. For thundersnow to occur, the air layer closer to the ground has to be warmer than the layers above, but still cold enough to create snow. During thundersnow events, heavy snowfall is to be expected. In some cases, two inches per hour is possible.

Click Here to see if there are any active warnings in your area.

Winter Storm Safety Tips
BEFORE A WINTER STORM: Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, emergency food supply, bottled water, battery-operated radio, flashlight, protective clothing, and blankets. Don't forget, be aware of changing weather. DURING A WINTER STORM: Stay indoors and dress warmly. Eat regularly, because food provides the body with energy for producing its own heat. Also, drink lots of water. If you must go outside, wear layered clothing, mittens and a hat. Watch for signs of hypothermia and frostbite. Remember to keep dry. Always change wet clothing to prevent the loss of body heat. If you must drive, carry a cell phone. Always, keep the gas tank full. Don't forget, let someone know where you're going, just in case your car gets stuck. If you're car gets stuck, stay with it and wait for help unless help is visible within 100 yards. Use maps and car mats to stay warm.

AFTER A WINTER STORM: Avoid driving until conditions have improved. Avoid overexertion! Heart attacks from shoveling snow are the leading cause of deaths during the winter. Also, check on neighbors to make sure they're okay.

Frost quakes are non-tectonic seismic events, meaning they are not caused by the shifting of the Earth's tectonic plates. Also known as cryoseisms, frost quakes are caused by a sudden rapid freezing of ground and bedrock, usually when temperatures go from above freezing to below zero. As moisture absorbed in the rock and soil freezes, it expands. This puts a great amount of stress on the areas around it. Eventually, the stress is too much and the soil and rock will crack in an "explosive" manner, creating a loud sound and even shaking the ground surface. Since temperatures are coldest in the overnight hours, most people experience frost quakes in the middle of the night. Winter Storm Activities
Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids investigate aspects of winter weather, such as temperature and wind. They familiarize themselves with weather-related words. It's a great activity for K-2nd graders.

Cold air moves over warm water and is warmed from below. Moisture evaporates in the air.

Warm moist air rises downwind of lakes and forms heavy snow.

Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids learn how winter storms form and about the different types of fronts. It's a great activity for 3rd-5th graders. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.
Measuring Snow Experiment: Here is a great experiment that lets kids measure snow. They let the snow melt and then measure it again. It teaches kids that snow is very dense and is why it holds more space than water.

The wind chill is the temperature your body feels when the air temperature is combined with the wind speed. The higher the wind speed the faster exposed areas of your body lose heat and the colder you feel.Melting Snow Experiment: Here is another experiment that teaches kids the difference between the freezing and melting process. It allows kids to take the temperature of a glass of snow. Then, watch the snow melt and observe how the temperature changed.

Frost Experiment: Here is a great experiment that lets kids make frost. They can see how dew turns into frost in a matter of minutes.Examining Snowflakes Experiment: Here is a great experiment that lets kids see snowflakes up close. They can examine the snowflake's six sides.
Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!
Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.
Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

Frostbite is damage to the skin due to prolonged exposure to cold temperatures, usually below 32° F.

WINTER STORM WATCH - Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm Watches are usually issued 12 to 48 hours before the beginning of a winter storm.

WINTER STORM WARNING - Issued when hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected.

BLIZZARD WARNING - Issued for sustained or gusty winds of 35 mph or more, and falling or blowing snow creating visibilities at or below 1/4 mile. These conditions should persist for 3 hours.

FROST/FREEZE WARNING - Issued when below freezing temperatures are expected.

LAKE EFFECT SNOW ADVISORY - Issued when accumulation of lake effect snow will cause significant inconvenience.

LAKE EFFECT SNOW WARNING - Issued when heavy lake effect snow is occurring.

WIND CHILL ADVISORY - Issued when the wind chill temperature is forecast to be between -15°F to -24°F.

WIND CHILL WARNING - Issued when the wind chill temperature is forecast to be -25°F or lower.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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A landslide includes a wide range of ground movements, such as rock falls, deep failure of slopes and shallow debris flows.

The biggest reason for a landslide is that there is a slope and material goes down the slope because of gravity.

But other things also contribute to landslides:

erosion by rivers, glaciers, or ocean waves makes slopes too steep

rock and soil slopes made weak through saturation by snowmelt or heavy rains

earthquakes that make weak slopes fail or crack the rocks that will eventually fall down

volcanic eruptions produce loose ash deposits, heavy rain, and debris flows

vibrations from machinery, traffic, blasting and even thunder may trigger failure of weak slopes

weight from much rain or snow, stockpiling of rock or ore, from waste piles, or from buildings may stress weak slopes to failure and other structures

groundwater pressure making the slope unstable

in shallow soils, the removal of deep-rooted plants that bind the colluvium to bedrock

An underlying reason is the nature of the material. For example, a thixotropic material such as mud or sand and water, can change from a gel to a sol by adding water or pressure, or shaking. It goes from being stable one minute to fluid the next minute. The greatest disasters, like lahars or mudslides, happen suddenly. It is possible for much of a volcano to just slide down suddenly, as with Toba, Krakatoa and Mount St Helens.

Other websites

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A landslide includes a wide range of ground movements, such as rock falls, deep failure of slopes and shallow debris flows. The biggest reason for a landslide is that there is a slope and material goes down the slope because of gravity.

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Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the shear strength of the slope material, an increase in the shear stress borne by the material, or a combination of the two. A change in the stability of a slope can be caused by a number of factors, acting together or alone. Natural causes of landslides include:

saturation by rain water infiltration, snow melting, or glaciers melting;

rising of groundwater or increase of pore water pressure (e.g. due to aquifer recharge in rainy seasons, or by rain water infiltration);

increase of hydrostatic pressure in cracks and fractures;

loss or absence of vertical vegetative structure, soil nutrients, and soil structure (e.g. after a wildfire - a fire in forests lasting for 3-4 days);

erosion of the top of a slope by rivers or sea waves;

physical and chemical weathering (e.g. by repeated freezing and thawing, heating and cooling, salt leaking in the groundwater or mineral dissolution);

ground shaking caused by earthquakes, which can destabilize the slope directly (e.g., by inducing soil liquefaction) or weaken the material and cause cracks that will eventually produce a landslide;

volcanic eruptions;

Landslides are aggravated by human activities, such as:

temporal variation in land use and land cover (LULC): it includes the human abandonment of farming areas, e.g. due to the economic and social transformations which occurred in Europe after the Second World War. Land degradation and extreme rainfall can increase the frequency of erosion and landslide phenomena.

Hungr-Leroueil-Picarelli classification

In traditional usage, the term landslide has at one time or another been used to cover almost all forms of mass movement of rocks and regolith at the Earth's surface. In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and subsidence processes. This scheme was later modified by Cruden and Varnes in 1996, and refined by Hutchinson (1988), Hungr et al. (2001), and finally by Hungr, Leroueil and Picarelli (2014). The classification resulting from the latest update is provided below.

Under this classification, six types of movement are recognized. Each type can be seen both in rock and in soil. A fall is a movement of isolated blocks or chunks of soil in free-fall. The term topple refers to blocks coming away by rotation from a vertical face. A slide is the movement of a body of material that generally remains intact while moving over one or several inclined surfaces or thin layers of material (also called shear zones) in which large deformations are concentrated. Slides are also sub-classified by the form of the surface(s) or shear zone(s) on which movement happens. The planes may be broadly parallel to the surface ("planar slides") or spoon-shaped ("rotational slides"). Slides can occur catastrophically, but movement on the surface can also be gradual and progressive. Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters. Slope deformations are slow, distributed movements that can affect entire mountain slopes or portions of it. Some landslides are complex in the sense that they feature different movement types in different portions of the moving body, or they evolve from one movement type to another over time. For example, a landslide can initiate as a rock fall or topple and then, as the blocks disintegrate upon the impact, transform into a debris slide or flow. An avalanching effect can also be present, in which the moving mass entrains additional material along its path.

Slope material that becomes saturated with water may produce a debris flow or mud flow. However, also dry debris can exhibit flow-like movement. Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing flooding along its path. This phenomenon is particularly hazardous in alpine areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on the slopes or result from the fluidization of landslide material as it gains speed or incorporates further debris and water along its path. River blockages as the flow reaches a main stream can generate temporary dams. As the impoundments fail, a domino effect may be created, with a remarkable growth in the volume of the flowing mass, and in its destructive power.

An earthflow is the downslope movement of mostly fine-grained material. Earthflows can move at speeds within a very wide range, from as low as 1 mm/yr to many km/h. Though these are a lot like mudflows, overall they are more slow-moving and are covered with solid material carried along by the flow from within. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. These flows are usually controlled by the pore water pressures within the mass, which should be high enough to produce a low shearing resistance. On the slopes, some earthflow may be recognized by their elongated shape, with one or more lobes at their toes. As these lobes spread out, drainage of the mass increases and the margins dry out, lowering the overall velocity of the flow. This process also causes the flow to thicken. Earthflows occur more often during periods of high precipitation, which saturates the ground and builds up water pressures. However, earthflows that keep advancing also during dry seasons are not uncommon. Fissures may develop during the movement of clayey materials, which facilitate the intrusion of water into the moving mass and produce faster responses to precipitation.

A rock avalanche, sometimes referred to as sturzstrom, is a large and fast-moving landslide of the flow type. It is rarer than other types of landslides but it is often very destructive. It exhibits typically a long runout, flowing very far over a low-angle, flat, or even slightly uphill terrain. The mechanisms favoring the long runout can be different, but they typically result in the weakening of the sliding mass as the speed increases. The causes of this weakening are not completely understood. Especially for the largest landslides, it may involve the very quick heating of the shear zone due to friction, which may even cause the water that is present to vaporize and build up a large pressure, producing a sort of hovercraft effect. In some cases, the very high temperature may even cause some of the minerals to melt. During the movement, the rock in the shear zone may also be finely ground, producing a nanometer-size mineral powder that may act as a lubricant, reducing the resistance to motion and promoting larger speeds and longer runouts. The weakening mechanisms in large rock avalanches are similar to those occurring in seismic faults.

Slides can occur in any rock or soil material and are characterized by the movement of a mass over a planar or curvilinear surface or shear zone.

A debris slide is a type of slide characterized by the chaotic movement of material mixed with water and/or ice. It is usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris. Debris flows and avalanches differ from debris slides because their movement is fluid-like and generally much more rapid. This is usually a result of lower shear resistances and steeper slopes. Debris slides generally begin with the detachment of rock chunks high on the slopes, which break apart as they slide towards the bottom.

Clay and silt slides are usually slow but can experience episodic acceleration in response to heavy rainfall or rapid snowmelt. They are often seen on gentle slopes and move over planar surfaces, such as over the underlying bedrock. Failure surfaces can also form within the clay or silt layer itself, and they usually have concave shapes, resulting in rotational slides

Shallow and deep-seated landslides

A landslide in which the sliding surface is located within the soil mantle or weathered bedrock (typically to a depth from few decimeters to some meters) is called a shallow landslide. Debris slides and debris flows are usually shallow. Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable soils. The low permeable soil traps the water in the shallower soil generating high water pressures. As the top soil is filled with water, it can become unstable and slide downslope.

Deep-seated landslides are those in which the sliding surface is mostly deeply located, for instance well below the maximum rooting depth of trees. They usually involve deep regolith, weathered rock, and/or bedrock and include large slope failures associated with translational, rotational, or complex movements. They tend to form along a plane of weakness such as a fault or bedding plane. They can be visually identified by concave scarps at the top and steep areas at the toe.

Causing tsunamis

Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis. Massive landslides can also generate megatsunamis, which are usually hundreds of meters high. In 1958, one such tsunami occurred in Lituya Bay in Alaska.

Related phenomena

An avalanche, similar in mechanism to a landslide, involves a large amount of ice, snow and rock falling quickly down the side of a mountain.

A pyroclastic flow is caused by a collapsing cloud of hot ash, gas and rocks from a volcanic explosion that moves rapidly down an erupting volcano.

Landslide prediction mapping

Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in the development of guidelines for sustainable land-use planning. The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship. The factors that have been used for landslide hazard analysis can usually be grouped into geomorphology, geology, land use/land cover, and hydrogeology. Since many factors are considered for landslide hazard mapping, GIS is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Cardenas reported evidence on the exhaustive use of GIS in conjunction of uncertainty modelling tools for landslide mapping. Remote sensing techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope, lithology, and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how the landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery.

Using satellite imagery in combination with GIS and on-the-ground studies, it is possible to generate maps of likely occurrences of future landslides. Such maps should show the locations of previous events as well as clearly indicate the probable locations of future events. In general, to predict landslides, one must assume that their occurrence is determined by certain geologic factors, and that future landslides will occur under the same conditions as past events. Therefore, it is necessary to establish a relationship between the geomorphologic conditions in which the past events took place and the expected future conditions.

Natural disasters are a dramatic example of people living in conflict with the environment. Early predictions and warnings are essential for the reduction of property damage and loss of life. Because landslides occur frequently and can represent some of the most destructive forces on earth, it is imperative to have a good understanding as to what causes them and how people can either help prevent them from occurring or simply avoid them when they do occur. Sustainable land management and development is also an essential key to reducing the negative impacts felt by landslides.

GIS offers a superior method for landslide analysis because it allows one to capture, store, manipulate, analyze, and display large amounts of data quickly and effectively. Because so many variables are involved, it is important to be able to overlay the many layers of data to develop a full and accurate portrayal of what is taking place on the Earth's surface. Researchers need to know which variables are the most important factors that trigger landslides in any given location. Using GIS, extremely detailed maps can be generated to show past events and likely future events which have the potential to save lives, property, and money.

Since the '90s, GIS have been also successfully used in conjunction to decision support systems, to show on a map real-time risk evaluations based on monitoring data gathered in the area of the Val Pola disaster (Italy).

Trackside rock slide detector on the UPRR Sierra grade near Colfax, CA

Prehistoric landslides

Storegga Slide, some 8,000 years ago off the western coast of Norway. Caused massive tsunamis in Doggerland and other countries connected to the North Sea. A total volume of 3,500 km3 (840 cu mi) debris was involved; comparable to a 34 m (112 ft) thick area the size of Iceland. The landslide is thought to be among the largest in history.

Landslide which moved Heart Mountain to its current location, the largest continental landslide discovered so far. In the 48 million years since the slide occurred, erosion has removed most of the portion of the slide.

Flims Rockslide, ca. 12 km3 (2.9 cu mi), Switzerland, some 10000 years ago in post-glacial Pleistocene/Holocene, the largest so far described in the alps and on dry land that can be easily identified in a modestly eroded state.

The landslide around 200 BC which formed Lake Waikaremoana on the North Island of New Zealand, where a large block of the Ngamoko Range slid and dammed a gorge of Waikaretaheke River, forming a natural reservoir up to 256 metres (840 ft) deep.

Cheekye Fan, British Columbia, Canada, ca. 25 km2 (9.7 sq mi), Late Pleistocene in age.

The Manang-Braga rock avalanche/debris flow may have formed Marsyangdi Valley in the Annapurna Region, Nepal, during an interstadial period belonging to the last glacial period. Over 15 km3 of material are estimated to have been moved in the single event, making it one of the largest continental landslides.

A massive slope failure 60 km north of Kathmandu Nepal, involving an estimated 10-15 km3. Prior to this landslide the mountain may have been the world's 15th mountain above 8000m.

Historical landslides

Main page: List of landslides

The 1806 Goldau landslide on September 2, 1806

The Cap Diamant Québec rockslide on September 19, 1889

Frank Slide, Turtle Mountain, Alberta, Canada, on 29 April 1903

Khait landslide, Khait, Tajikistan, Soviet Union, on July 10, 1949

A Magnitude 7.5 earthquake in Yellowstone Park (August 17, 1959) caused a landslide that blocked the Madison River, and created Quake Lake.

Monte Toc landslide (260 million cubic metres, 9.2 billion cubic feet) falling into the Vajont Dam basin in Italy, causing a megatsunami and about 2000 deaths, on October 9, 1963

Hope Slide landslide (46 million cubic metres, 1.6 billion cubic feet) near Hope, British Columbia on January 9, 1965.

The 1966 Aberfan disaster

Tuve landslide in Gothenburg, Sweden on November 30, 1977.

The 1979 Abbotsford landslip, Dunedin, New Zealand on August 8, 1979.

The eruption of Mount St. Helens (May 18, 1980) caused an enormous landslide when the top 1300 feet of the volcano suddenly gave way.

Val Pola landslide during Valtellina disaster (1987) Italy

Thredbo landslide, Australia on 30 July 1997, destroyed hostel.

Vargas mudslides, due to heavy rains in Vargas State, Venezuela, in December, 1999, causing tens of thousands of deaths.

2005 La Conchita landslide in Ventura, California causing 10 deaths.

2007 Chittagong mudslide, in Chittagong, Bangladesh, on June 11, 2007.

2008 Cairo landslide on September 6, 2008.

disaster caused 37 deaths, on October 1.

The 2010 Uganda landslide caused over 100 deaths following heavy rain in Bududa region.

Zhouqu county mudslide in Gansu, China on August 8, 2010.

Devil's Slide, an ongoing landslide in San Mateo County, California

2011 Rio de Janeiro landslide in Rio de Janeiro, Brazil on January 11, 2011, causing 610 deaths.

2014 Pune landslide, in Pune, India.

2014 Oso mudslide, in Oso, Washington

2017 Mocoa landslide, in Mocoa, Colombia

Extraterrestrial landslides

Evidence of past landslides has been detected on many bodies in the solar system, but since most observations are made by probes that only observe for a limited time and most bodies in the solar system appear to be geologically inactive not many landslides are known to have happened in recent times. Both Venus and Mars have been subject to long-term mapping by orbiting satellites, and examples of landslides have been observed on both planets.

In Spanish: Corrimiento de tierra para niños

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What is a landslide?
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope due to gravity. The materials may move by falling, toppling, sliding, spreading, or flowing.

What causes a landslide?
Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Landslides can be triggered by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors.

What are submarine landslides?
Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas.

Where do landslides occur?
Landslides in the United States occur in all 50 States. The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. Alaska and Hawaii also experience all types of landslides.

How fast do landslide travel?
Landslides can move slowly, (millimeters per year) or can move quickly and disastrously, as is the case with debris flows. Debris flows can travel down a hillside at speeds up to 200 miles per hour (more commonly, 30 - 50 miles per hour), depending on the slope angle, water content, volume of debris, and type of earth and debris in the flow. These flows are initiated by heavy periods of rainfall, but sometimes can happen as a result of short bursts of concentrated rainfall or other factors in susceptible areas. Burned areas charred by wildfires are particularly susceptible to debris flows, given certain soil characteristics and slope conditions.

Why study landslides?
Landslides are a serious geologic hazard. It is estimated that in the United States they cause in excess of $1 billion in damages and from about 25 to 50 deaths each year. Globally, landslides cause billions of dollars in damages and thousands of deaths and injuries each year.

Who is most at risk for landslides?
As people move into new areas of hilly or mountainous terrain, it is important to understand the nature of their potential exposure to landslide hazards, and how cities, towns, and counties can plan for land-use, engineering of new construction and infrastructure, and other measures which will reduce the costs of living with landslides. Although the physical causes of many landslides cannot be removed, geologic investigations, good engineering practices, and effective enforcement of land-use management regulations can reduce landslide hazards.

Do human activities cause landslides?
Yes, in some cases human activities can be a contributing factor in causing landslides. Many human-caused landslides can be avoided or mitigated. They are commonly a result of building roads and structures without adequate grading of slopes, of poorly planned alteration of drainage patterns, and of disturbing old landslides.

Where can I find landslide information for my area?
The USGS National Landslide Information Center (NLIC) is a part of the U.S. Geological Survey Landslide Hazards Program that collects and distributes all forms of information related to landslides. The NLIC is designed to serve landslide researchers, geotechnical practitioners engaged in landslide stabilization, and anyone else concerned in any way with landslide education, hazard, safety, and mitigation. Every state in the US has a geoscience agency and most have some landslide information. The Association of American State Geologists provides links to the State Geologist for every state.

What was the most expensive landslide to fix in the United States?
The Thistle, Utah, landslide cost in excess of $200 million dollars to fix. The landslide occurred during the spring of 1983, when unseasonably warm weather caused rapid snowmelt to saturate the slope. The landslide destroyed the railroad tracks of the Denver and Rio Grande Western Railway Company, and the adjacent Highway 89. It also flowed across the Spanish Fork River, forming a dam. The impounded river water inundated the small town of Thistle. The inhabitants of the town of Thistle, directly upstream from the landslide, were evacuated as the lake began to flood the town, and within a day the town was completely covered with water. Populations downstream from the dam were at risk because of the possible overtopping of the landslide by the lake. This could cause a catastrophic outburst of the dam with a massive flood downstream. Eventually, a drain system was engineered to drain the lake and avert the potential disaster.

How many deaths result from landslides?
An average of between 25 and 50 people are killed by landslides each year in the United States. The worldwide death toll per year due to landslides is in the thousands. Most landslide fatalities are from rock fall, debris-flows, or volcanic debris flows.

What should I know about wildfires and debris flows?
Wild land fires are inevitable in the western United States. Expansion of human development into forested areas has created a situation where wildfires can adversely affect lives and property, as can the flooding and landslides that occur in the aftermath of the fires. There is a need to develop tools and methods to identify and quantify the potential hazards posed by landslides produced from burned watersheds. Post-fire landslide hazards include fast-moving, highly destructive debris flows that can occur in the years immediately after wildfires in response to high intensity rainfall events, and those flows that are generated over longer time periods accompanied by root decay and loss of soil strength. Post-fire debris flows are particularly hazardous because they can occur with little warning, can exert great impulsive loads on objects in their paths, and can strip vegetation, block drainage ways, damage structures, and endanger human life. Wildfires could potentially result in the destabilization of pre-existing deep-seated landslides over long time periods.

How do landslides cause tsunamis?
Tsunamis are large, potentially deadly and destructive sea waves, most of which are formed as a result of submarine earthquakes. They may also result from the eruption or collapse of island or coastal volcanoes and the formation of giant landslides on marine margins. These landslides, in turn, are often triggered by earthquakes. Tsunamis can be generated on impact as a rapidly moving landslide mass enters the water or as water displaces behind and ahead of a rapidly moving underwater landslide.

What are some examples of landslides that have caused tsunamis?
The 1964 Alaska earthquake caused 115 deaths in Alaska alone, with 106 of those due to tsunamis generated by tectonic uplift of the sea floor, and by localized subareal and submarine landslides. The earthquake shaking caused at least 5 local slide-generated tsunamis within minutes after the shaking began. An eyewitness account of the tsunami caused by the movement and landslides of the 1964 Alaska earthquake.

Research in the Canary Islands concludes that there have been at least five massive volcano landslides that occurred in the past, and that similar large events may occur in the future. Giant landslides have the potential of generating large tsunami waves at close and also very great distances and would have the potential to devastate large areas of coastal land as far away as the eastern seaboard of North America.

Rock falls and rock avalanches in coastal inlets, such as those that have occurred in the past at Tidal Inlet, Glacier Bay National Park, Alaska, have the potential to cause regional tsunamis that pose a hazard to coastal ecosystems and human settlements. On July 9, 1958, a magnitude M 7.9 earthquake on the Fairweather Fault triggered a rock avalanche at the head of Lituya Bay, Alaska. The landslide generated a wave that ran up 524 m on the opposite shore and sent a 30-m high wave through Lituya Bay, sinking two of three fishing boats and killing two persons.

How soon does the danger of landslides end after the rain stops?
It's not possible to exactly predict the number of days or weeks that landslides remain a danger after heavy rain. Residents near mountain slopes, canyons, and landslide prone areas should stay alert even after heavy rain subsides.

Why is southern California vulnerable to landslides?
Areas that have been burned by recent wildfires are highly susceptible to debris-flow activity that can be triggered by significantly less rainfall than that which triggers debris flows from unburned hill slopes.

What was the biggest landslide in the world?
The world's biggest historic landslide occurred during the 1980 eruption of Mount St. Helens, a volcano in the Cascade Mountain Range in the State of Washington, USA. The volume of material was 2.8 cubic kilometers (km).

What was the biggest prehistoric landslide?
The world's biggest prehistoric landslide, discovered so far on land, is in southwestern Iran, and is named the Saidmarreh landslide. The landslide is located on the Kabir Kuh anticline in Southwest Iran at 33 degrees north latitude, 47.65 degrees east longitude. The landslide has a volume of about 20 cubic kilometers, a depth of 300 m, a travel distance of 14 km and a width of 5 km. This means that about 50 billion tons of rock moved in this single event!

Rotational slide: This is a slide in which the surface of rupture is curved concavely upward and the slide movement is roughly rotational about an axis that is parallel to the ground surface and transverse across the slide.

Translational slide: In this type of slide, the landslide mass moves along a roughly planar surface with little rotation or backward tilting.

Block slide: is a translational slide in which the moving mass consists of a single unit or a few closely related units that move downslope as a relatively coherent mass.

Fall: Falls are abrupt movements of masses of geologic materials, such as rocks and boulders, that become detached from steep slopes or cliffs. Separation occurs along discontinuities such as fractures, joints, and bedding planes, and movement occurs by free-fall, bouncing, and rolling. Falls are strongly influenced by gravity, mechanical weathering, and the presence of interstitial water.

Topple: Toppling failures are distinguished by the forward rotation of a unit or units about some pivotal point, below or low in the unit, under the actions of gravity and forces exerted by adjacent units or by fluids in cracks.

Debris flow: A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilize as a slurry that flows downslope. Debris flows include less than 50% fines. Debris flows are commonly caused by intense surface-water flow, due to heavy precipitation or rapid snowmelt, that erodes and mobilizes loose soil or rock on steep slopes. Debris flows also commonly mobilize from other types of landslides that occur on steep slopes, are nearly saturated, and consist of a large proportion of silt- and sand-sized material. Debris-flow source areas are often associated with steep gullies, and debris-flow deposits are usually indicated by the presence of debris fans at the mouths of gullies. Fires that denude slopes of vegetation intensify the susceptibility of slopes to debris flows.

Debris avalanche: This is a variety of very rapid to extremely rapid debris flow.

Earthflow: Earthflows have a characteristic "hourglass" shape. The slope material liquefies and runs out, forming a bowl or depression at the head. The flow itself is elongate and usually occurs in fine-grained materials or clay-bearing rocks on moderate slopes and under saturated conditions. However, dry flows of granular material are also possible.
Mudflow: A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand-, silt-, and clay-sized particles. In some instances, for example in many newspaper reports, mudflows and debris flows are commonly referred to as "mudslides."

Creep: Creep is the imperceptibly slow, steady, downward movement of slope-forming soil or rock. Movement is caused by shear stress sufficient to produce permanent deformation, but too small to produce shear failure. There are generally three types of creep: (1) seasonal, where movement is within the depth of soil affected by seasonal changes in soil moisture and soil temperature; (2) continuous, where shear stress continuously exceeds the strength of the material; and (3) progressive, where slopes are reaching the point of failure as other types of mass movements. Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges.

Lateral Spreads: Lateral spreads are distinctive because they usually occur on very gentle slopes or flat terrain. The dominant mode of movement is lateral extension accompanied by shear or tensile fractures. The failure is caused by liquefaction, the process whereby saturated, loose, cohesionless sediments (usually sands and silts) are transformed from a solid into a liquefied state. Failure is usually triggered by rapid ground motion, such as that experienced during an earthquake, but can also be artificially induced. When coherent material, either bedrock or soil, rests on materials that liquefy, the upper units may undergo fracturing and extension and may then subside, translate, rotate, disintegrate, or liquefy and flow. Lateral spreading in fine-grained materials on shallow slopes is usually progressive. The failure starts suddenly in a small area and spreads rapidly. Often the initial failure is a slump, but in some materials movement occurs for no apparent reason. Combination of two or more of the above types is known as a complex landslide.

SLIDES: Although many types of mass movements are included in the general term "landslide," the more restrictive use of the term refers only to mass movements, where there is a distinct zone of weakness that separates the slide material from more stable underlying material. The two major types of slides are rotational slides and translational slides.

FLOWS: There are five basic categories of flows that differ from one another in fundamental ways. Although there are multiple types of causes of landslides, the three that cause most of the damaging landslides around the world are these:

Landslides and Water: Slope saturation by water is a primary cause of landslides. This effect can occur in the form of intense rainfall, snowmelt, changes in ground-water levels, and waterlevel changes along coastlines, earth dams, and the banks of lakes, reservoirs, canals, and rivers. Landsliding and flooding are closely allied because both are related to precipitation, runoff, and the saturation of ground by water. In addition, debris flows and mudflows usually occur in small, steep stream channels and often are mistaken for floods; in fact, these two events often occur simultaneously in the same area. Landslides can cause flooding by forming landslide dams that block valleys and stream channels, allowing large amounts of water to back up. This causes backwater flooding and, if the dam fails, subsequent downstream flooding. Also, solid landslide debris can "bulk" or add volume and density to otherwise normal streamflow or cause channel blockages and diversions creating flood conditions or localized erosion. Landslides can also cause overtopping of reservoirs and/or reduced capacity of reservoirs to store water.

Landslides and Seismic Activity: Many mountainous areas that are vulnerable to landslides have also experienced at least moderate rates of earthquake occurrence in recorded times. The occurrence of earthquakes in steep landslide-prone areas greatly increases the likelihood that landslides will occur, due to ground shaking alone or shaking- caused dilation of soil materials, which allows rapid infiltration of water. The 1964 Great Alaska Earthquake caused widespread landsliding and other ground failure, which caused most of the monetary loss due to the earthquake. Other areas of the United States, such as California and the Puget Sound region in Washington, have experienced slides, lateral spreading, and other types of ground failure due to moderate to large earthquakes. Widespread rockfalls also are caused by loosening of rocks as a result of ground shaking. Worldwide, landslides caused by earthquakes kill people and damage structures at higher rates than in the United States.

Landslides and Volcanic Activity: Landslides due to volcanic activity are some of the most devastating types. Volcanic lava may melt snow at a rapid rate, causing a deluge of rock, soil, ash, and water that accelerates rapidly on the steep slopes of volcanoes, devastating anything in its path. These volcanic debris flows (also known as lahars) reach great distances, once they leave the flanks of the volcano, and can damage structures in flat areas surrounding the volcanoes. The 1980 eruption of Mount St. Helens, in Washington triggered a massive landslide on the north flank of the volcano, the largest landslide in recorded times.

Landslide Mitigation - How to Reduce the Effects of Landslides: Vulnerability to landslide hazards is a function of location, type of human activity, use, and frequency of landslide events. The effects of landslides on people and structures can be lessened by total avoidance of landslide hazard areas or by restricting, prohibiting, or imposing conditions on hazard-zone activity. Local governments can reduce landslide effects through land-use policies and regulations. Individuals can reduce their exposure to hazards by educating themselves on the past hazard history of a site and by making inquiries to planning and engineering departments of local governments. They can also obtain the professional services of an engineering geologist, a geotechnical engineer, or a civil engineer, who can properly evaluate the hazard potential of a site, built or unbuilt.

The hazard from landslides can be reduced by avoiding construction on steep slopes and existing landslides, or by stabilizing the slopes. Stability increases when groundwater is prevented from rising in the landslide mass by (1) covering the landslide with an impermeable membrane, (2) directing surface water away from the landslide, (3) draining groundwater away from the landslide, and (4) minimizing surface irrigation. Slope stability is also increased when a retaining structure and/ or the weight of a soil/rock berm are placed at the toe of the landslide or when mass is removed from the top of the slope.

LANDSLIDE ADVISORY - a general statement about the potential of landslide activity in a given region relative to developing rainfall predictions. An advisory may include general statements about rainfall conditions that can lead to debris-flow activity, and list precautions to be taken in the event of heavy rainfall.

LANDSLIDE WATCH - means that landslide-activity will be possible, but is not imminent. People in, or planning to travel through, a watch area should check preparedness and stay informed about developing weather patterns.

LANDSLIDE WARNING - indicates that landslide activity is presently occurring and extreme caution should be taken.

FLOOD WATCH - means that an overflow of water from a river is possible for your area.

FLASH FLOOD WATCH - means that flash flooding is possible in or close to the watch area. Flash Flood Watches can be put into effect for as long as 12 hours, while heavy rains move into and across the area.

FLOOD WARNING - means flooding conditions are actually occurring in the warning area.

FLASH FLOOD WARNING - means that flash flooding is actually occurring in the warning area. A warning can also be issued as a result of torrential rains, a dam failure or snow thaw.

URBAN and SMALL STREAM ADVISORY - means flooding of small streams, streets and low-lying areas, such as railroad underpasses and urban storm drains is occurring.

DEBRIS - The scattered remains of something broken or destroyed; rubble or wreckage.

DEBRIS FLOW - A churning, water-saturated mass of rock, soil and organic matter that rushes down mountain slopes, typically originating as a landslide.

GRAVITY - The natural force of attraction exerted by a celestial body, such as Earth, upon objects at or near its surface, tending to draw them toward the center of the body.

FRICTION - Force that resists the relative motion or tendency to such motion of two bodies in contact.

TRIGGER - An event that initiates a landslide.

Click Here to see if there are any active warnings in your area.

BEFORE A LANDSLIDE: Avoid building near steep slopes, close to mountain edges, near drainage ways, or natural erosion valleys. Get a ground assessment of your property. Landslides occur where they have before, and in identifiable hazard locations. Ask for information on landslides in your area, specific information on areas vulnerable to landslides, and request a professional referral for a very detailed site analysis of your property, and corrective measures you can take, if necessary. Watch the patterns of storm-water drainage near your home, and note the places where runoff water converges, increasing flow in channels. These are areas to avoid during a storm. Make evacuation plans. Plan at least two evacuation routes since roads may become blocked or closed. Develop your own emergency plan for your family or business.

MINIMIZE HOME HAZARDS: Have flexible pipe fittings installed to avoid gas or water leaks, as flexible fittings are more resistant to breakage. Plant ground cover on slopes and build retaining walls. In mudflow areas, build channels or deflection walls to direct the flow around buildings. Remember: If you build walls to divert debris flow and the flow lands on a neighbor's property, you may be liable for damages. Design and construction of walls and channels strong enough to resist or divert landslides is highly specialized work, best done by qualified professionals.

DURING A STORM/LANDSLIDE: Stay alert and awake. Many debris-flow fatalities occur when people are sleeping. Listen to a NOAA Weather Radio or portable, battery-powered radio or television for warnings of intense rainfall. Be aware that intense, short bursts of rain may be particularly dangerous, especially after longer periods of heavy rainfall and damp weather. If you are in areas susceptible to landslides and debris flows, consider leaving if it is safe to do so. Remember that driving during an intense storm can be hazardous. If you remain at home, move to a second story if possible. Staying out of the path of a landslide or debris flow saves lives. Listen for any unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together. A trickle of flowing or falling mud or debris may precede larger landslides. Moving debris can flow quickly and sometimes without warning. If you are near a stream or channel, be alert for any sudden increase or decrease in water flow and for a change from clear to muddy water. Such changes may indicate landslide activity upstream, so be prepared to move quickly. Don't delay! Save yourself, not your belongings. Be especially alert when driving. Bridges may be washed out, and culverts overtopped. Do not cross flooding streams...Turn Around, Don't Drown! Embankments along roadsides are particularly susceptible to landslides. Watch the road for collapsed pavement, mud, fallen rocks, and other indications of possible debris flows. Be aware that strong shaking from earthquakes can induce or intensify the effects of landslides.

AFTER A LANDSLIDE: Stay away from the slide area. There may be danger of additional slides. Check for injured and trapped persons near the slide area. Give first aid if trained. Remember to help your neighbors who may require special assistance-infants, elderly people, and people with disabilities. Listen to a battery-operated radio or television for the latest emergency information. Remember that flooding may occur after a mudflow or a landslide. Check for damaged utility lines. Report any damage to the utility company. Check the building foundation, chimney, and surrounding land for damage. Replant damaged ground as soon as possible since erosion caused by loss of ground cover can lead to flash flooding. Seek the advice of geotechnical expert for evaluating landslide hazards or designing corrective techniques to reduce landslide risk.

Lesson Plan: Here is a great lesson plan on erosion and landslides.

Lesson Plan: Here is a great lesson plan on landslides for grades 6-8.

Lesson Plan: This lesson consists of landslides, liquefaction, and structural failure caused by earthquakes.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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What is a landslide? A landslide is defined as the movement of a mass of rock, debris, or earth down a slope due to gravity. The materials may move by falling, toppling, sliding, spreading, or flowing. What causes a landslide? Almost every landslide has multiple causes.

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What is a hurricane?
A hurricane is a huge storm! It can be up to 600 miles across and have strong winds spiraling inward and upward at speeds of 75 to 200 mph. Each hurricane usually lasts for over a week, moving 10-20 miles per hour over the open ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye" in the Northern Hemisphere and clockwise direction in the Southern Hemisphere. The center of the storm or "eye" is the calmest part. It has only light winds and fair weather. When they come onto land, the heavy rain, strong winds and large waves can damage buildings, trees and cars.

How do hurricanes form?
Hurricanes only form over really warm ocean water of 80°F or warmer. The atmosphere (the air) must cool off very quickly the higher you go. Also, the wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis Force is needed to create the spin in the hurricane and it becomes too weak near the equator, so hurricanes can never form there.
Hurricane Tracking Charts
Atlantic Ocean
Eastern Pacific

What is storm surge?
Storm surges are frequently the most devastating element of a hurricane. As a hurricane's winds spiral around and around the storm, they push water into a mound at the storm's center. This mound of water becomes dangerous when the storm reaches land because it causes flooding along the coast. The water piles up, unable to escape anywhere but on land as the storm carries it landward. A hurricane will cause more storm surge in areas where the ocean floor slopes gradually. This causes major flooding.
As you watch the storm-surge animations, notice the effect that the physical geography of each coastline has on storm surge. Also, note the waves on top of the ocean's surface. Wind, waves, and sea-level rise all contribute to storm-surge damage.

Shallow-Water Coastline

Deep-Water Coastline

With technology the way it is, there are computer models that allow forecasters to predict the amount of storm surge that will affect a coastal area. These are called Slosh Models and take into account a storm's strength, its path, how the ocean shallows, and the shape of the land. Then it calculates how much storm surge a hurricane will probably cause.

When does hurricane season start?
The Atlantic hurricane season is from June 1 to November 30, but most hurricanes occur during the fall months. The Eastern Pacific hurricane season is from May 15 to November 30. (Below is a graphic that shows you when hurricanes are most active across parts of the world.)

Who names hurricanes?
From 1950 to 1952, tropical cyclones of the North Atlantic Ocean were identified by the phonetic alphabet (Able-Baker-Charlie-etc.), but in 1953 the US Weather Bureau switched to women's names. The rest of the world eventually caught on, and naming rights now go by the World Meteorological Organization, which uses different sets of names depending on the part of the world the storm is in. Around the U.S., only women's names were used until 1979, when it was decided that they should alternate a list that included men's names too. There's 6 different name lists that alternate each year. If a hurricane does significant damage, its name is retired and replaced with another.
Atlantic Hurricane Names
Eastern Pacific Hurricane Names

What is the difference between a hurricane and a typhoon?
Nothing except geography. Tropical storms occur in several of the world's oceans, and except for their names, they are essentially the same type of storm. In the Atlantic Ocean, Gulf of Mexico, and the Eastern Pacific Ocean, they are called hurricanes. In the Western Pacific Ocean, they are called typhoons. In the Indian Ocean, the Bay of Bengal, and Australia, these types of storms are called cyclones.

Who are the "Hurricane Hunters"?
The brave "hurricane hunters" work for the National Oceanic and Atmospheric Administration (NOAA). Each mission lasts about ten hours, with the crews passing four to six times through the storm. The planes carry radar, sophisticated computers, and weather instruments that determine characteristics such as temperature, air pressure, wind speed, and wind direction inside the hurricane. The crews also release instruments that measure temperature, air pressure, and wind at different levels as the devices drop through the hurricane toward the ocean. By mission's end, NOAA can warn everyone in the hurricane's path. Below is a photo of the hurricane hunters taking measurements inside Hurricane Katrina.

What is coastal beach erosion?
Coastal beach erosion is the wearing away of land, the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage. Waves are generated by storms, wind, or hurricanes and can cause coastal erosion. This may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments.

TROPICAL STORM WATCH - Tropical Storm conditions with sustained winds from 39 -74 mph are possible in your area within the next 36 hours.

TROPICAL STORM WARNING - Tropical Storm conditions are expected in your area within the next 24 hours.

HURRICANE WATCH - Hurricane conditions with sustained winds of 74 mph or greater are possible in your area within the next 36 hours. This WATCH should trigger your family's disaster plan, and protective measures should be initiated. Especially, those actions that require extra time such as securing a boat and leaving a barrier island.

HURRICANE WARNING - Hurricane conditions are expected in your area within 24 hours. Once this WARNING has been issued, your family should be in the process of completing protective actions and deciding the safest location to be during the storm.

COASTAL FLOOD WATCH - The possibility exists for the inundation of land areas along the coast within the next 12 to 36 hours.

COASTAL FLOOD WARNING - Land areas along the coast are expected to become, or have become, inundated by sea water above the typical tide action.

SMALL CRAFT ADVISORY - A small craft advisory is a type of warning issued by the National Weather Service, most frequently in coastal areas. It is issued when winds have reached, or are expected to reach within 12 hours, a speed marginally less than that which is considered gale force, usually 25-38 mph.

Click Here to see if there are any active warnings in your area.

Tropical Wave - A low pressure trough moving generally westward with the trade winds.

Tropical Disturbance - An organized area of thunderstorms that usually forms in the tropics. Typically, they maintain their identity for 24 hours and are accompanied by heavy rains and gusty winds.

Tropical Cyclone - A generic term for any organized low pressure that develops over tropical and sometimes sub-tropical waters. Tropical depressions, tropical storms, and hurricanes are all example of tropical cyclones.

Tropical Depression - An organized area of low pressure in which sustained winds are 38 mph or less.

Tropical Storm - A tropical cyclone with maximum sustained wind speeds that range from 39 to 73 mph.

Hurricane - A tropical cyclone with sustained winds of at least 74 mph.

To learn more about hurricanes, Click Here to watch a variety of videos teaching you the ins and outs of nature's fury. I would like to give a special thanks to Pinellas County Emergency management for putting these instructional videos together.

BEFORE A HURRICANE: Have a disaster plan and a pet plan ready. Before a storm threatens, contact your veterinarian or local humane society for information on preparing your pets for an emergency. Board up windows and bring in outdoor objects that could blow away. Make sure you know which county or parish you live in and know where all the evacuation routes are. Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water. Have a NOAA weather radio handy with plenty of batteries, so you can listen to storm advisories. Have some cash handy as well, because following a hurricane, banks and ATMs may be temporarily closed. Make sure your car is filled with gasoline.

DURING A HURRICANE: Stay away from low-lying and flood prone areas. Always stay indoors during a hurricane, because strong winds will blow things around. Leave mobile homes and to go to a shelter. If your home isn't on higher ground, go to a shelter. If emergency managers say to evacuate, then do so immediately.

AFTER A HURRICANE: Stay indoors until it is safe to come out. Check for injured or trapped people, without putting yourself in danger. Watch out for flooding which can happen after a hurricane. Do not attempt to drive in flooding water. Stay away from standing water. It may be electrically charged from underground or downed power lines. Don't drink tap water until officials say its safe to do so.

Stay alert to storm advisories by using your NOAA weather radio.

Enact your family disaster plan.

Map out your route. Use travel routes specified by local authorities.

Do not get on the road without a place to go.

Fill your car with gasoline.

Enact your pet plan. Before a storm threatens, contact your veterinarian or local humane society for information on preparing your pets for an emergency.

Bring your disaster supply kit. Make sure you include important documents. Have enough food and water for at least 3 days. Bring flashlights for emergency lightning, since it's likely that there will be power outages and most places will be running on backup power.

Secure your home before leaving. Board up windows and glass doors, anchor loose objects or bring them inside and lock your doors.

Have some cash handy. Following a hurricane, banks and ATMs may be temporarily closed.

Notify your family and friends of your plans.

WHEN EVACUATING:

If possible, evacuate to the home of either friends or family in a non-vulnerable area within your county or parish.

Next, try a hotel.

As a last result, go to a public shelter. Remember, shelters are not designed for comfort and do not usually accept pets.

Here is a list of what what you will need for 3 to 5 days if you chose to stay at your home during a hurricane.

Drinking Water Battery-operated Weather Radio

Canned Food Portable Alarm Clock

Manual Can Opener Extra Batteries

Extra Prescription Medicine Flashlights

Eating Utensils Rope

First Aid Kit Hammer and Nails

Trash Bags Duct Tape

Cash Extension Cords

Pillows and Blankets Tarp

Sleeping Bags Mosquito Repellent

Water Jugs Cleaning Supplies

As far as tools are concerned, the following are a must. Remember, power tools may be useless for several days after a storm.

Hand Saw (8 or 10 point)

Claw Hammer

Shovel

Push Broom

Screw Drivers

Limb Saw (pruning saw)

Vice Grips

Utility Knife

Cotton Work Gloves

Lesson Plan: Here is a great lesson plan on learning about hurricane safety. In this activity, Owlie teaches kids about hurricanes and quizzes them about what they learned. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Lesson Plan: Here is a great lesson plan on understanding hurricanes. Students will learn how wind speed increases the height and why higher waves occur in shallower water. This activity is for grades 6-8.

Lesson Plan: Here is a great lesson plan on elementary reading comprehension. This lesson contains a broader vocabulary, more hurricane facts, and more thought-provoking writing prompts. It works well for grades 3-5. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Lesson Plan: Here is a great interactive lesson plan on allowing kids to create their very own hurricane. It lets you try to create ideal hurricane conditions by changing the winds, latitude, moisture, and sea temperature. It even keeps score! This is a great activity for 5-8th graders.

Lesson Plan: Here is a great interactive lesson plan that lets kids aim a hurricane. It lets you move the hurricane symbol, high pressure symbol and low pressure symbol to track your very own hurricane. Sometimes your hurricane will make landfall, other times it misses the U.S. all together. It lets kid understand how important the setup of weather impacts where hurricanes go.

Suck An Egg Into A Bottle Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!

Make Your Own Barometer I Experiment: Here is an experiment that allows the kids to make a barometer.

Make Your Own Barometer II Experiment: Here is an experiment that allows the kids to make a barometer.

Create Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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What is a hurricane? A hurricane is a huge storm! It can be up to 600 miles across and have strong winds spiraling inward and upward at speeds of 75 to 200 mph. Each hurricane usually lasts for over a week, moving 10-20 miles per hour over the open ocean.

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Hurricanes are severe tropical storms that form in the southern Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern Pacific Ocean. They collect heat and energy through contact with warm ocean waters and then move toward land. Evaporation from the ocean water increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye," which is the center of the hurricane.

Hurricanes have winds at least 74 miles per hour. When hurricanes come onto land, their heavy rain, strong winds, and large waves can damage buildings, trees, and cars. Storm surge is when rising water moves inland, or away from the coastline. It's very dangerous.

Words to Know

Inland - Away from the coastline.

Am I at Risk?

What Can I Do?

Before

During

After

Learn More

Did you know?

Hurricanes can also affect areas greater than 100 miles away from the coastline. People who live inland are also at risk for wind, thunderstorms, tornadoes, and flooding.

Helpful Links

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Words to Know Am I at Risk? What Can I Do? Learn More

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The wind at the beach is whipping at 95 miles an hour. Waves 16 feet tall are crashing down. Even sharks are heading out to calmer waters. A hurricane is on its way.

These powerful storms have different names depending on where in the world they form. They're called hurricanes if they occur in the Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and eastern Pacific Ocean. In the western Pacific Ocean, they're known as typhoons; in the southern Pacific and Indian Oceans, they're called cyclones.

Scientists know them all as tropical cyclones. As many as 150 occur around the world each year.

How a hurricane forms

Hurricanes are strong storms that start in the ocean and have winds of at least 74 miles an hour. In the Northern Hemisphere (the part of Earth north of the equator), hurricanes generally occur between mid-August to late October. In the Southern Hemisphere (the area south of the equator), storm season is between April and December, with peak storm activity around May and November. During these times, oceans have warmer water, which is what a hurricane needs to form.

Hurricanes begin when a tropical depression forms in the ocean. A tropical depression is a line of rain showers and weak thunderstorms that circle around an area of low air pressure. If the water is at least 79°F, a hurricane might form.

The low air pressure causes the hot, humid air from the ocean to rise in a spiral shape. As that warm air rises, it releases heat, cools down, and condenses into gusty bands of clouds and storms. The low-pressure area continues to suck up hot, moist air, and the spiral gets stronger and faster.

When winds reach 39 miles an hour, the tropical depression becomes a tropical storm. When winds reach 74 miles an hour, it's officially a hurricane.

As a hurricane moves over cooler water or hits land, it loses the warm water that fuels it and begins to weaken. But dangerous winds can still cause damage, and storm surges-when a strong storm pushes ocean water ashore-can flood coastal areas with more than 20 feet of water. Heavy rains and floods can continue far inland.

Understanding a hurricane's strength

Hurricanes are classified by wind speed and the amount of damage that scientists predict the storm will cause when it reaches land. (In the United States, this is done by the National Hurricane Center, part of the National Oceanic and Atmospheric Administration.)

For example, a Category 1 storm has wind speeds of 74 to 95 miles an hour and will probably damage some homes and cause a few power outages. But a Category 5 hurricane is considered a powerful, destructive storm. These storms have winds of 156 miles an hour or more and will likely cause so much damage that people must abandon their communities, which will need months to clean up.

These rankings can help predict the severity of an approaching storm, but any hurricane can be devastating. For instance, Hurricane Katrina was only a Category 3 storm when it hit the U.S. Gulf Coast around Louisiana and Mississippi in 2005. The storm caused over $100 billion in damages, and nearly 2,000 people died.

Predicting the path

Meteorologists can predict the path that a hurricane will travel-and where it will make landfall-by analyzing changes in temperature, cloud formations, and air circulation patterns. That data is gathered by specialized aircraft, satellites, and weather surveillance radar from above the Earth. Other scientific devices that float in the ocean can measure winds, waves, and air and sea temperatures.

The information from these tools is used to create computer forecasting models used by scientists to learn when a storm is forming, where it might travel, and how severe it will be. That can help local officials release warnings or even evacuation orders in order to keep people safe from the coming hurricane.

Naming hurricanes

Once a storm's wind speed reachers 39 miles an hour, it becomes a tropical storm and is given a name. The name is chosen from a list of about 20 names issued by the World Meteorological Organization at the beginning of the hurricane season. They alternate between female and male names.

But you won't see David, Katrina, Andrew, or Laura on that list-those hurricanes were so destructive that the names have been removed. And you won't hear of any hurricanes starting with Q, U, X, Y, or Z, since few names begin with those letters.

More powerful storms in the future?

In the future, scientists don't expect to see more hurricanes, but they do expect more powerful ones. That's because hurricanes get bigger more quickly in warmer water. As climate change causes ocean temperatures to rise, scientists predict that future hurricanes will be rainier and longer lasting.

How to survive a hurricane

The safest thing to do is to follow local instructions and leave the area, or evacuate, if officials say you should. Here are other tips for staying safe if a hurricane is headed your way.

Before a hurricane
* Know the evacuation routes in your neighborhood, and make sure your parents have put gas in the car.
* Check your yard to see if any branches are broken on trees and alert an adult if they are. (Those branches could break off and soar through a window!)
* Bring in anything that could blow away, like garbage cans and outdoor furniture.
* Close all your windows, storm shutters, blinds, and curtains.

During a hurricane
* If you haven't evacuated, stay indoors where it's safe.
* Fill all bathtubs and sinks with clean, cold water in case water lines are damaged or the supply becomes contaminated.
* Ride out the storm in an interior room, such as a hallway or closet on the lowest level of your house.
* Never go near a window, even if it's boarded up.
* If it looks like the storm is going to hit your home, lie on the floor under a table or another sturdy object.
* Limit the use of cell phones to free up space for emergency calls.

After a hurricane
* Listen to weather reports to make sure the storm has passed. A calm sky might be just the hurricane's eye, or center, and more storm fun will be on the way.
* If you evacuated, return only when officials say it's safe.
* Check all food for spoilage. Remember: If in doubt, throw it out.

Adapted from the Nat Geo Kids book Extreme Weather by Thomas Kostigen, revised for digital by Laura Goertzel

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The wind at the beach is whipping at 95 miles an hour. Waves 16 feet tall are crashing down. Even sharks are heading out to calmer waters. A hurricane is on its way. These powerful storms have different names depending on where in the world they form.

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Science >> Earth Science for Kids

Weather - Hurricanes (Tropical Cyclones)

What is a hurricane?

A hurricane is a large rotating storm with high speed winds that forms over warm waters in tropical areas. Hurricanes have sustained winds of at least 74 miles per hour and an area of low air pressure in the center called the eye.

Different Names for Hurricanes

The scientific name for a hurricane is a tropical cyclone. Tropical cyclones go by different names in different places. In North America and the Caribbean they are called "hurricanes", in the Indian Ocean they are called "cyclones", and in Southeast Asia they are called "typhoons."

How do hurricanes form?

Hurricanes form over the warm ocean water of the tropics. When warm moist air over the water rises, it is replaced by cooler air. The cooler air will then warm and start to rise. This cycle causes huge storm clouds to form. These storm clouds will begin to rotate with the spin of the Earth forming an organized system. If there is enough warm water, the cycle will continue and the storm clouds and wind speeds will grow causing a hurricane to form.

Parts of a Hurricane

Eye - At the center of the hurricane is the eye. The eye is an area of very low air pressure. There are generally no clouds in the eye and the wind is calm. Don't let this fool you, however, the most dangerous part of the storm is at the edge of the eye called the eye wall.

Eye wall - Around the outside of the eye is a wall made up of very heavy clouds. This is the most dangerous part of the hurricane and where the highest speed winds are. The winds at the eye wall can reach speeds of 155 miles per hour.

Rainbands - Hurricanes have large spirally bands of rain called rainbands. These bands can drop huge amounts of rainfall causing flooding when the hurricane hits land.

Diameter - Hurricanes can become huge storms. The diameter of the hurricane is measured from one side to the other. Hurricanes can span a diameter of over 600 miles.

Height - The storm clouds that power hurricanes can become very tall. A powerful hurricane can reach nine miles into the atmosphere.

The structure of a hurricane

Where do tropical cyclones occur?

Tropical cyclones occur over the ocean in areas near the equator. This is because there is plenty of warm water in these areas to allow the storms to form. There are seven major areas in the world that tend to produce tropical cyclones. See the map below.

Locations of tropical cyclones throughout the world

When do hurricanes occur?

Hurricanes that form in the Caribbean and the Atlantic Ocean occur between June 1st and November 30th each year. This is called hurricane season.

Why are hurricanes dangerous?

When hurricanes strike land they can cause huge amounts of damage. Most of the damage is caused by flooding and storm surge. Storm surge is when the ocean level rises at the coastline due to the power of the storm. Hurricanes also cause damage with high speed winds that can blow downtrees and damage homes. Many hurricanes can develop several small tornados as well.

How are they named?

Hurricanes in the Atlantic are named based on a list of names maintained by the World Meteorological Organization. The names go in alphabetical order and the storms are named as they appear. So the first storm of the year will always have a name that starts with the letter "A." There are six lists of names and each year a new list is used.

Categories

Tropical cyclones are categorized according to the speed of sustained winds.

Tropical Depression - 38 mph or less

Tropical Storm - 39 to 73 mph

Hurricane

Category 1 - 74 to 95 mph

Category 2 - 96 to 110 mph

Category 3 - 111 to 129 mph

Category 4 - 130 to 156 mph

Category 5 - 157 or higher mph

Interesting Facts about Hurricanes

Hurricanes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. This is due to the rotation of the Earth called the Coriolis effect.

The letters Q, U, X, Y, and Z are not used for the first letter when naming hurricanes.

The names are alternated between boy and girl names.

Weather forecasters draw a cone showing where they think the hurricane is most likely to travel.

You can always find out the latest information on hurricanes at the website of the National Hurricane Center which tracks and forecasts hurricanes.

Activities

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Kids learn about hurricanes (Tropical Cyclones) including how they form, names, eye, eye wall, rainbands, locations, seasons, facts, and categories.

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Hurricanes - Learning about Hurricanes for kids and children

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What is a tsunami?
A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tsunamis are NOT tidal waves. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water. With typical waves, water flows in circles, but with a tsunami, water flows straight. This is why tsunamis cause so much damage!

How are tsunamis generated?
Tsunamis are generated by any large, impulsive displacement of the sea level. The most common cause of a tsunami is sea floor uplift associated with an earthquake. Tsunamis are also triggered by landslides into or under the water surface, and can be generated by volcanic activity and meteorite impacts.

How often do tsunamis occur?
On the average, two tsunamis occur per year throughout the world which inflict damage near the source. Approximately every 15 years a destructive, ocean-wide tsunami occurs.

Can strike-slip (horizontal motion) earthquakes trigger tsunamis?
Yes, approximately 10-15% of damaging tsunamis are triggered by strike-slip earthquakes. This type of earthquake is less likely to trigger a tsunami than one with vertical motion. The waves are likely generated by associated landslides or motion of a sloping bathymetric feature. Tsunamis generated by strike-slip earthquakes normally affect regions near the source only.

What does the word "tsunami" mean?
Tsunami (soo-NAH-mee) is a Japanese word meaning harbor wave.

How fast do tsunamis travel?
Tsunami velocity depends on the depth of water through which it travels. Velocity equals the square root of the product of the water depth times the acceleration of gravity. Tsunamis travel approximately 475 mph in 15,000 feet of water. In 100 feet of water the velocity drops to about 40 mph.

Did you know...A tsunami travels from the central Aleutian Islands to Hawaii in about 5 hours and to California in about 6 hours, or from the Portugal coast to North Carolina in about 8.5 hours.

How big is a tsunami?
Tsunamis range in size from inches to over a hundred feet. In deep water (greater than 600 feet), tsunamis are rarely over 3 feet and are not normally noticed by ships due to their long period or time between crests. As tsunamis propagate into shallow water, the wave height can increase by over 10 times. Tsunami heights vary greatly along a coast. The waves can be amplified by shoreline and sea floor features. A large tsunami can flood low-lying coastal land over a mile from the coast.

What does a tsunami look like when it reaches shore?
Normally, a tsunami appears as a rapidly advancing or receding tide. In some cases, a wall of water or series of breaking waves may form.

How is a tsunami different from a wind-generated wave?
Wind-generated waves usually have periods or time between crests between 5 and 15 seconds. Tsunami periods normally range from 5 to 60 minutes. Also, wind-generated waves break as they shoal and lose energy offshore. Tsunamis act more like a flooding wave. A twenty foot tsunami is a twenty foot rise in sea level.

What are nature's signs that a tsunami may be imminent?
There are a few signs like hard ground shaking for 20+ seconds near the coast or a sudden sea level withdrawal. Tsunamis may be accompanied by loud, booming noises.

Can earthquakes and tsunamis be predicted?
No, earthquakes cannot be predicted. Once an earthquake has occurred, the arrival time of a tsunami, if generated, can be determined accurately. There is not normally enough time to accurately predict tsunami heights near the source. Away from the source, tsunami wave heights can be estimated based on mathematical tsunami models and observed wave heights.

Aerial video of the tsunami that devastated Japan on March 11, 2011.

Click Here to see an animation of an earthquake and the resulting tsunami. It's great for kids, because they get to see how it actually happens!
What are some of the most damaging tsunamis?

Japan: Major tsunami in 2011 generated in the Pacific Ocean.

Asia: Asian tsunami in 2004 generated in the Indian Ocean.

Alaska: Major tsunamis were generated along the Alaskan coast in 1946, 1957, 1958, 1964, and 1965. Many other locally generated tsunamis occurred prior to those dates.

US/Canada West Coast: Tsunamis were generated locally in 1812, 1873, 1878, 1927, 1930, 1946 and 1949. The west coast was also impacted by tsunamis generated in other regions in 1877, 1946, 1952, 1957, 1960, 1964, 1975, 2006, and 2010.

US/Canada Atlantic Coast: Tsunamis were recorded in 1755, 1884, 1886, and 1929.

Puerto Rico and the Virgin Islands experienced damaging tsunamis in 1867 and 1918.

Click Here for the NOAA/National Geophysical Data Center tsunami catalog.

TSUNAMI WARNING- A tsunami warning indicates that a tsunami may be imminent and that coastal locations in the warned area should prepare for flooding. The initial warning is typically based solely on seismic information. After the tsunami is recorded on sea level gages, the warning will be cancelled, restricted, expanded, or downgraded to an advisory. Warnings indicate that flooding up to the maximum expected limit is possible and residents should follow their local emergency management instructions. Warnings are issued when the earthquake information or tsunami forecasts indicate that a wave over 1 meter in amplitude is expected, possible, or ongoing.

TSUNAMI ADVISORY- A tsunami advisory indicates a tsunami which may produce strong currents and is dangerous to those in or very near the water is expected. Large inundations are not expected in areas under advisory status. Advisories will be cancelled, extended, or upgraded to a warning depending on the event severity. Advisories are issued when the tsunami forecast is in the range of 0.3 to 1 meter, or an observed tsunami is in the range of 0.5 to 1.0 meters.

TSUNAMI WATCH- A tsunami watch is an early alert issued to areas which may later be impacted by a tsunami. Tsunami impact is normally at least three hours away for regions within a tsunami watch. The watch will either be upgraded to a warning or advisory in subsequent messages or cancelled depending on the severity of the tsunami. People within a watch area should stay alert for further information regarding tsunami threat.

CREST - The top of a wave.

FJORD - A narrow sea inlet between cliffs or steep slopes.

SURGE - A large wave or billow.

TROUGH - The lowest point between waves.

Click Here to get the latest tsunami warning information from the NWS.

PLAN FOR A TSUNAMI: Have a disaster plan. Know whether you're at risk for danger. Plan an evacuation route. Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water.

DURING A TSUNAMI: Follow the instructions issued by local authorities. You will probably want to evacuate immediately. Get to higher ground and as far inland as you can.

AFTER A TSUNAMI: Help injured or trapped people. Stay out of a building if water remains around it. Tsunami waters can cause buildings to sink, floors to crack, or walls to collapse. When re-entering homes, use extreme caution. Check for gas leaks. Open windows and doors to help dry things out. Look for fire hazards.

Lesson Plan: Here is a great lesson plan on learning about tsunamis. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Lesson Plan: Here is a great lesson plan on tracking a tsunami.

Lesson Plan: Here is a great lesson plan on tsunamis and how they devastating effects they may cause in the world.

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What is a tsunami? A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tsunamis are NOT tidal waves. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water.

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While tsunamis came to the forefront of the world's attention when the 2004 Boxing Day Tsunami hit the coast of Sumatra, they have taken place several times in the past. There are very destructive and deadliest tsunamis in terms of loss of lives caused by them or magnitude.
Sumatra, Indonesia - 26 December 2004
A colossal earthquake with a 9.1 magnitude struck the coast of Sumatra on December 26, 2004 resulting in an ensuing tsunami which killed an estimated 230,000 people and caused US$10b in property damage. Known as the 2004 Indian Ocean tsunami, this tsunami reached to a height of 50 m and travelled 5 km inland near Meubolah, Sumatra and caused destruction in as a many as 14 countries.
Lisbon, Portugal -1 November 1755
The colossal earthquake that took place in Lisbon in 1755, registered 9.0 on the Richter scale. That quake in this coastal city of Portugal and much of Europe triggered a tsunami that killed as many as 100,000 people in Portugal, Spain and Morocco. The incident cased extensive damage to Lisbon which lost one fourth of its populace. The famous philosopher Voltaire penned a poem on this colossal loss of life.
North Pacific Coast, Japan - 11 March 2011
A powerful tsunami generated by an earthquake of 9.0 magnitude over the east coast of Japan resulting in the death of over 18,000 people. According to the estimates of the World Bank, it will take five years to financially overcome the $235 billion damages.

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Prince William Sound, Alaska - 27 March, 1964
The Alaskan Good Friday earthquake which is considered to be the largest one in North America resulted in a tsunami that travelled at a speed of over 400 mph. Though the loss of life was just more than 100 people, the tsunami caused extensive damage to large parts of the Alaskan coastline. The earthquake had a magnitude of 9.2.
Krakatau, Indonesia - 27 August 1883
Eruptions from the Krakatau caldera volcano triggered tsunamis and shockwaves that killed about 40,000 people. Several waves as high as 37 m swept the Indonesian Islands of southern Sumatra and western Java and destroyed the towns of Merak and Anjer.

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Easy Science for Kids World's Biggest Tsunamis - learn fun facts about animals, the human body, our planet and much more. Fun free World's Biggest Tsunamis activities!

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Did you know?

"Tsunami" is a Japanese word. Tsu means "harbor" and nami means "wave."

On the open spaces of the ocean, a fast-moving tsunami may only be a few feet high, with 100 miles separating wave crests. As they approach shore, waves increase in height and currents intensify, which create a bigger threat to life and property.

Few tsunamis "break" like the waves seen in wind-generated waves popular with surfers. Tsunamis are more often associated with strong currents and walls of water that do not retreat like normal tidal waves do.

Tsunamis may be local, regional, or far away. The type of tsunami depends on the location of where the tsunami started and where it may hit land.

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Kids can learn tsunami facts, as well as if they’re at risk of experiencing a tsunami and what they can do to prepare.

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Kids learn about tsunamis including what causes them such as earthquakes, where they occur, why they are dangerous, and what happens during a tsunami event.

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A student doing an experiment in the rock physics lab.

A trench dug across a fault to learn about past earthquakes.

A GPS instrument measures slow movements of the ground.

A scientist stands in front of a fault scarp in southern California.

Damage to badly-constructed buildings after an earthquake.

Scientists doing field work and looking at their notes.

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USGS Earthquake Hazards Program, responsible for monitoring, reporting, and researching earthquakes and earthquake hazards

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Javascript must be enabled to view our earthquake maps. To access USGS earthquake information without using javascript, use our Magnitude 2.5+ Earthquakes, Past Day ATOM Feed or our other earthquake feeds.

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Javascript must be enabled to view our earthquake maps. To access USGS earthquake information without using javascript, use our Magnitude 2.5+ Earthquakes, Past Day ATOM Feed or our other earthquake feeds.

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What is an earthquake?
Earthquakes are the shaking, rolling or sudden shock of the earth's surface. They are the Earth's natural means of releasing stress. More than a million earthquakes rattle the world each year. The West Coast is most at risk of having an earthquake, but earthquakes can happen in the Midwest and along the East Coast. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted - although scientists are working on it!

Click Here to learn more about earthquakes from USGS.

What causes an earthquake?
There are about 20 plates along the surface of the earth that move continuously and slowly past each other. When the plates squeeze or stretch, huge rocks form at their edges and the rocks shift with great force, causing an earthquake. Think of it this way: Imagine holding a pencil horizontally. If you were to apply a force to both ends of the pencil by pushing down on them, you would see the pencil bend. After enough force was applied, the pencil would break in the middle, releasing the stress you have put on it. The Earth's crust acts in the same way. As the plates move they put forces on themselves and each other. When the force is large enough, the crust is forced to break. When the break occurs, the stress is released as energy which moves through the Earth in the form of waves, which we feel and call an earthquake.

Click Here to see an animation of an earthquake. It's great for kids, because they get to see how it actually happens!

What is a fault?
A fault is an area of stress in the earth where broken rocks slide past each other, causing a crack in the Earth's surface. There are the major types of faults: dip-slip normal, dip-slip reverse, strike-slip, and oblique-slip.

What are plate tectonics?
The theory of plate tectonics is a interesting story of continents drifting from place to place breaking apart, colliding, and grinding against each other. The plate tectonic theory is supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. (See plate tectonic graphic above.) The plates are all moving in different directions and at different speeds. Sometimes the plates crash together, pull apart or sideswipe each other. When this happens, it commonly results in earthquakes.

Continental Drift: To see this animation again, click on the picture! This animation shows you what our planet looked like millions of years ago and what it looks like now! Graphic Credit: Geology Department at University of California, Berkeley

Click Here to learn more about plate tectonics and the drifting of our continents.

What is a seismograph?
A seismograph is an instrument used for recording the intensity and duration of an earthquake.

Click Here to calculate the strength of earthquakes!

What is a tsunami?
A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tsunamis are NOT tidal waves. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water. With typical waves, water flows in circles, but with a tsunami, water flows straight. This is why tsunamis cause so much damage!

Aerial video of the tsunami that devastated Japan on March 11, 2011.

Click Here to see an animation of an earthquake and the resulting tsunami. It's great for kids, because they get to see how it actually happens!

Click Here to get the latest tsunami warning information from the NWS.

Click Here for tsunami safety information.

EPICENTER - The point on the earth's surface directly above the source of the earthquake.

SEISMIC WAVES - The energy created by the quake travels in waves from the epicenter, where they are the strongest. The waves shake buildings, structures and the earth vertically, causing them to move horizontally!

RICHTER SCALE - A measurement of an earthquake's intensity. Each one-point increase on the scale indicates ten times the amount of shaking and 33 times the amount of energy. The energy released by a large earthquake may be equal to 10,000 times the energy of the first atomic bomb.

Click Here to see if there has been any recent earthquake activity across the U.S.

Earthquakes are measured by their intensity on the Richter Scale. Each one-point increase on the scale indicates ten times the amount of shaking and 33 times the amount of energy.

Click Here to learn about cool earthquake facts!

BEFORE AN EARTHQUAKE: Have a disaster plan. Emergency preparedness can save lives. Choose a safe place in every room. It's best to get under a sturdy piece of furniture like a table or a desk where nothing can fall on you. Practice DROP, COVER AND HOLD ON! Drop under something sturdy, hold on, and protect your eyes by pressing your face against your arm. If you live in an earthquake prone area, bolt tall furniture to the wall and install strong latches to cupboards. Prepare a first aid kit for your home. By taking special precautions and checking for hazards before a disaster strikes, you will be much more likely to stay safe.

DURING AN EARTHQUAKE: DROP, COVER AND HOLD ON! Stay indoors until the shaking stops. Stay away from windows. If you're in bed, hold on and stay there, protecting your head with a pillow. If you're outdoors, find a clear spot away from buildings, trees and power lines. Then, drop to the ground. If you're in a car, slow down and drive to a safe place. Stay in the car until the shaking stops.

AFTER THE SHAKING STOPS: Check for injuries. Inspect your home for damage. Eliminate fire hazards, so turn off the gas if you think its leaking. Expect aftershocks. Each time you feel one, DROP, COVER AND HOLD ON.

Lesson Plan: Here is a great lesson plan on learning about how thrust faults are responsible for the uplift of many mountain ranges across the world, including the Los Angeles Basin. This is a great lesson plan for middle and high school students.

Lesson Plan: Here is a great lesson plan keeping track of earthquakes around the world. In this activity, kids keep a record of the location of earthquakes for a week and learn about plate tectonics.

Earthquake Experiment: Here is a great experiment that explains how to prepare for an earthquake.

Science Fair Project Ideas: Here is a list of science fair project ideas that deal with earthquakes.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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What is an earthquake? Earthquakes are the shaking, rolling or sudden shock of the earth's surface. They are the Earth's natural means of releasing stress. More than a million earthquakes rattle the world each year. The West Coast is most at risk of having an earthquake, but earthquakes can happen in the Midwest and along the East Coast.

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The ground shakes, buildings tumble and the earth heaves and cracks. Serious earthquakes are terrifying and dangerous, but are rare in the U.S. But why do earthquakes happen? The earth is made up of four layers - the inner core, outer core, mantle and crust. The mantle and crust are a thin skin compared to the other layers.

The mantle is about 1,750 miles thick, while the crust is only about 8 miles thick. This thin skin is broken into pieces called tectonic plates. The plates are like puzzle pieces, floating on top of the Earth's inner core. Sometimes the pieces slide under or against each other and become stuck.

When the pieces slide apart, they create tremendous force. This force causes the earth to shake and ripple. Over 80 percent of the earth's earthquakes happen in the Pacific Ocean, in a place known as the "Ring of Fire." Annually, around 10,000 people die in earthquakes every year. Most of the deaths happen when people are trapped in falling buildings. After an earthquake, mudslides, fires and tsunamis can also hurt people.

Fun Facts All About Earthquakes for Kids

Alaska, California and Hawaii have the most earthquakes in the U.S. Other western states, like Nevada, Idaho, Washington and Oregon are prone to earthquakes or can be damaged by earthquakes that happen in Alaska and California.

Alaska has more earthquakes than any other U.S. state. It has experienced over 12,000 earthquakes in the last 30 years. Alaska is followed by California, Hawaii, Nevada, Washington, Idaho, Wyoming, Montana and Utah.

Underneath the Earth's surface lie tectonic plates. These plates move and shift over time. Sometimes they slide under one another or push up against each other, creating enormous stress. When they move again, they cause an earthquake.

Scientists who study earthquakes are called seismologists.

Seismologists can tell how serious an earthquake is by a machine called a seismogram, which rates the intensity of the quake's shaking.

Scientists can use special instruments to record an earthquake's strength. An earthquake rated 3 to 5 is minor; an earthquake rated 5 to 7 is moderate to strong; an earthquake rated 7 to 8 is major; an earthquake rated 8 or above is great.

On average, one earthquake measuring 8 or above happens every year.

The area near Japan in the Pacific Ocean has the most earthquakes in the world. This area also has a lot of volcanoes. It is called the Ring of Fire.

Most people who die in earthquakes die when buildings collapse on them. Others die in floods, fires or mudslides that happen after the earthquake.

May 22nd 1960 in Valdivia Chile the largest ever recorded Earthquake measuring a whopping 9.5 magnitude struck.

December 26th 2004 an Earthquake in the Indian Ocean measuring a magnitude of 9.1 on the Richter Scale resulted in a massive Tsunami hitting the region which resulted in the deaths of over 230,000 people.

March 11th 2011 off the coast of Honshu Japan a magnitude 9.0 earthquake caused a massive Tsunami to hit the coast. The Tsunami caused over 18,000.

On our planet earth we have four different types of dip-slip-faults and they are Normal - Reverse - Thrust - Strike Up.

Earthquake Vocabulary

Learn More All About Earthquakes and Why They Happen

Imagine that you're sitting in school when the ground begins to shake. Books fall off the shelves and you might even be thrown from your chair. That's what happens when an earthquake occurs. Earthquakes are the most deadly of all natural disasters. Over 10,000 people die every year in earthquakes.

Easy Science All About Earthquakes for Kids Video

Watch this interesting video all about earthquakes:

Earthquake Q&A

Question: Do all earthquakes cause damage?

Answer: Most earthquakes cause only minor shaking. Southern California has about 10,000 earthquakes every year. Some of them are so mild people don't even feel them.

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Question: What can I do to be safe in an earthquake?

Answer: If you're in a building in an earthquake, get under a table or desk and hold onto it. If you're outside, move to an open area away from trees, buildings or power lines.

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Question: What should I do to keep safe in an earthquake?

Answer: The best way to survive an earthquake is to take cover under a sturdy table. Get down low and place your hands over your head. You can even duck down in a door frame or curl up next to a couch or bed. Don't go outside, though. Many people die from falling debris.

Enjoyed the Natural Science for Kids website all about Earthquakes info? Take the FREE & fun all about Earthquakes quiz and download FREE all about Earthquakes worksheet for kids. For lengthy info click here.

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All About Earthquakes and Why They Happen Fun Science Facts for Kids. Learn more all about Earthquakes through our Easy Earth Science for Kids website.

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An earthquake is the sudden, quick shaking of the earth. It is caused by rock breaking and moving under the ground. Additional earthquakes, known as aftershocks, can occur for hours, days, or even months after an earthquake. These are usually smaller than the first earthquake. However, they could cause more damage to structures weakened by the first earthquake.

Earthquakes can also cause tsunamis. Tsunamis are a series of waves caused by a large and sudden disturbance of the sea.

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The "Ring of Fire' is the zone surrounding the Pacific Ocean where about 90% of the world's earthquakes occur.

The Richter Scale measures the strength of an earthquake. It goes from 0.0 (none) to 10.0.

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In Alaska in 1964, a magnitude 9.2 earthquake jarred the earth so strongly it caused fishing boats to sink in Louisiana. What causes the ground tremble like that? The answer is simple. The Earth's surface is on the move.

The surface of the earth, called the "crust," is not one solid piece. It's more like a 20 piece puzzle. Each puzzle piece is called a "plate." The plates constantly move. Fortunately for us, they don't move fast. Geologists estimate the fastest plate might shift 6 inches a year (15 centimeters). That's about as fast as your hair grows.

Earthquakes happen when a plate scrapes, bumps, or drags along another plate. When does this happen? Constantly. About a half-million quakes rock the Earth every day. That's millions a year. People don't feel most of them because the quake is too small, too far below the surface, or deep in the sea. Some, however, are so powerful they can be felt thousands of miles away.

A powerful earthquake can cause landslides, tsunamis, flooding, and other catastrophic events. Most damage and deaths happen in populated areas. That's because the shaking can cause windows to break, structures to collapse, fire, and other dangers.

Geologists cannot predict earthquakes. They hope they will in the future through continued research and improved technology.

Earthquakes can happen anytime or anywhere. But you can prepare for the unpredictable with a family safety plan, emergency kit, and supplies.

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In Alaska in 1964, a magnitude 9.2 earthquake jarred the earth so strongly it caused fishing boats to sink in Louisiana. What causes the ground tremble like that? The answer is simple. The Earth's surface is on the move. The surface of the earth, called the "crust," is not one solid piece.

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Kid's learn about the science of earthquakes. What causes them and where they happen.

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What is a volcano?
A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. Gases and rock shoot up through the opening and spill over or fill the air with lava fragments. Eruptions can cause lateral blasts, lava flows, hot ash flows, mudslides, avalanches, falling ash and floods. Volcano eruptions have been known to knock down entire forests. An erupting volcano can trigger tsunamis, flash floods, earthquakes, mudflows and rockfalls.

Click Here to learn more about volcanoes from USGS.

How are volcanoes formed?
Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.

What are the different stages of volcanoes?
Scientists have categorized volcanoes into three main categories: active, dormant, and extinct. An active volcano is one which has recently erupted and there is a possibility that it may erupt soon. A dormant volcano is one which has not erupted in a long time but there is a possibility it can erupt in the future. An extinct volcano is one which has erupted thousands of years ago and there's no possibility of eruption.

Why do volcanoes erupt?
The Earth's crust is made up of huge slabs called plates, which fit together like a jigsaw puzzle. These plates sometimes move. The friction causes earthquakes and volcanic eruptions near the edges of the plates. The theory that explains this process is called plate tectonics.

What are plate tectonics?
The theory of plate tectonics is a interesting story of continents drifting from place to place breaking apart, colliding, and grinding against each other. The plate tectonic theory is supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. The plates are all moving in different directions and at different speeds. Sometimes the plates crash together, pull apart or sideswipe each other. When this happens, it commonly results in earthquakes.
Click Here to learn more about plate tectonics and the drifting of our continents.

How many volcanoes are there?
There are more than 1500 active volcanoes on the Earth. We currently know of 80 or more which are under the oceans. Active volcanoes in the U.S. are found mainly in Hawaii, Alaska, California, Oregon and Washington.

What is the difference between lava and magma?
Magma is liquid rock inside a volcano. Lava is liquid rock (magma) that flows out of a volcano. Fresh lava glows red hot to white hot as it flows.

Why does lava take a long time to cool down?
Lava cools slowly because lava is a poor conductor of heat. Lava flows slow down and thicken as they harden.

What is a pyroclastic flow?
A pyroclastic flow is a fluidized mixture of solid to semi-solid fragments and hot, expanding gases that flows down the sides of a volcano. These awesome features are heavier-than-air emulsions that move much like a snow avalanche, except that they are fiercely hot, contain toxic gases, and move at phenomenal, hurricane-force speeds. They are the most deadly of all volcanic phenomena.

What is lahar?
A lahar is a type of mudflow or debris flow composed of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. It is very dangerous because it's consistency and the way it acts is very much like cement. It is liquid when it's moving, but when it stops, it solidifies. This can cause just as much devastation as lava itself.

What is pumice?
Pumice is a light, porous volcanic rock that forms during explosive eruptions. It resembles a sponge because it consists of a network of gas bubbles frozen amidst fragile volcanic glass and minerals. All types of magma (basalt, andesite, dacite, and rhyolite) will form pumice.

What is the largest active volcano?
The world's largest, active volcano is Mauna Loa in Hawaii, where famous coffee is grown in the rich volcanic soils. Mauna Loa is 13,677 feet above sea level. From its base below sea level to its summit, Mauna Loa is taller than Mount Everest.

What is the Ring of Fire?
The Pacific Ring of Fire is an area of frequent earthquakes and volcanic eruptions encircling the basin of the Pacific Ocean. The Ring of Fire has 452 volcanoes and is home to over 50% of the world's active and dormant volcanoes. Ninety percent of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire.

What is volcanic lightning?
Volcanic lightning, also known as dirty thunderstorms, is capable of producing some of the most powerful and visually striking lightning storms on Earth. Not all volcanic eruptions produce lightning. When it does occur, a single eruption can create multiple, separate lightning storms. The lightning seems to be set off by explosions during the eruption, although not all explosions cause lightning. During recent eruptions that displayed lightning, scientists observed the most intense lightning occurred at the beginning of the eruption and gradually decreased as the eruption continued, sometimes over a period of weeks.

When is a volcano considered active?
Surprisingly, there is no consensus among volcanologists on how to define an active volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes meaningless when compared to the lifespans of humans or even civilizations. For example, many of Earth's volcanoes have erupted dozens of times in the past few thousand years but are not currently showing signs of activity. Given the long lifespan of such volcanoes, they are very active. By our lifespans, however, they are not.

What is a Vulcanian Eruption?
A vulcanian eruption is a type of explosive eruption that ejects new lava fragments that do not take on a rounded shape during their flight through the air. This may be because the lava is too viscous or already solidified. These moderate-sized explosive eruptions commonly eject a large proportion of volcanic ash and also breadcrust bombs and blocks.

What is a mud volcano?
In volcanic regions, mud volcanoes are usually small volcano-shaped cones of mud. They are built as mud erupts from a vent, either as a flowing liquid or ejected into the air. The mud is formed as acid gases rise through the crust, react with rock and turn it into clay. The mud is a mixture of clay and groundwater. The mud volcanoes erupt following pressurization from geothermal steam and gases.

What is a tsunami?
A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tsunamis are NOT tidal waves. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water. With typical waves, water flows in circles, but with a tsunami, water flows straight. This is why tsunamis cause so much damage!

Click Here to see an animation of an earthquake and the resulting tsunami. It's great for kids, because they get to see how it actually happens!
Click Here to get the latest tsunami warning information from the NWS.

What is the difference between active, dormant and extinct volcanoes?

Active volcanoes - Scientists usually consider a volcano active if it is currently erupting or showing signs of unrest, such as unusual earthquake activity or significant new gas emissions. Many scientists also consider a volcano active if it has erupted in historic time. It's important to note that the span of recorded history differs from region to region; in the Mediterranean, recorded history reaches back more than 3,000 years but in the Pacific Northwest of the United States, it reaches back less than 300 years, and in Hawaii, little more than 200 years.

Dormant volcanoes - Dormant volcanoes are those that are not currently active (as defined above), but could become restless or erupt again.

Extinct volcanoes - Extinct volcanoes are those that scientists consider unlikely to erupt again. Whether a volcano is truly extinct is often difficult to determine. For example, since calderas have lifespans sometimes measured in millions of years, a caldera that hasn't produced an eruption in tens of thousands of years is likely to be considered dormant instead of extinct. Yellowstone caldera in Yellowstone National Park is at least 2 million years old and hasn't erupted for 70,000 years, yet scientists do not consider Yellowstone as extinct. In fact, because the caldera has frequent earthquakes, a very active geothermal system, and rapid rates of ground uplift, many scientists consider it to be a very active volcano.

What are the different types of volcanoes?
Volcanoes are grouped into four types: cinder cones, composite volcanoes, and shield volcanoes.

Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown into the air, cooled and fallen around the vent.

Composite volcanoes which are also called 'stratovolcanoes' are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris. Mt. Rainier and Mount St. Helens are examples of this type of volcano.

Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. Basalt lava flows from these volcanoes are called flood basalts. The volcanoes that formed the basalt of the Columbia Plateau were shield volcanoes.

When did Mount St. Helens erupt?
On May 18, 1980, Mount St. Helens erupted. It's located in southwestern Washington State in the Cascade Range. The blast was heard as far away as Montana, Idaho, Canada and California. Fifty-seven people died and the eruption caused $1.2 billion in damage.

Click Here for more info on Mount St. Helens.

What are some other notable volcano eruptions?
Krakatoa was a dormant volcano in Indonesia, which awakened and produced one of the biggest volcanic eruptions in 1883. So massive was the eruption that the sound of it was heard as far away as Australia. It's widely reported as the loudest sound heard in recorded history. The Krakatoa eruption created a huge amount of ash cloud which covered the Earth and reduced global temperatures for 5 years! A total of 40,000 people died in that explosion and an entire chain of the volcanic island was destroyed. For more info: Click Here!

Mount Pelee was a dormant volcano situated in the Caribbean island of Martinique. In 1902, it erupted in a massive horizontal explosion sending huge clouds of ash released towards the nearby town of Saint-Pierre. The side of the volcano exploded and lava flowed straight into the town, killing 30,000 people in a matter of minutes. It is regarded as one of the biggest and most devastating volcanic eruptions of the 20th century, a benchmark for future eruptions.

Mount Fujiyama, also popularly known as Mount Fuji, is an active volcano which last erupted in 1708. It is incidentally the tallest mountain in Japan. If you are visiting Tokyo, the capital of Japan, look in the west on a clear day and you will be able to see Mount Fuji. It is an iconic volcano. Mount Fuji is 3,776 meters high and it is snow clad throughout the year, with five lakes surrounding it. Currently in a state of dormancy, there has not been any eruption reported for more than 300 years. The last known eruption lasted for about 3 weeks during which it covered the surrounding villages with ash and cinders. Mount Fuji is now a popular tourist location with a large number of climbers actively scaling the mountain top.

MAGMA - Magma is the liquid rock inside a volcano.

LAVA - Lava is the liquid rock (magma) that flows out of a volcano. Lava glows red hot to white hot as it flows.

ACTIVE VOLCANO - An active volcano is one that erupts regularly.

DORMANT VOLCANO - A dormant volcano is one that has not erupted for many years, although there is still some activity deep inside.

EXTINCT VOLCANO - An extinct volcano is a volcano that is no longer active.

GEYSERS - Geysers are springs that throw boiling water high in the air. They are caused by volcanic heat warming trapped ground water.

ASH - Ash are very small fragments of lava or rock blasted into the air by volcanic explosions.

PUMICE - It is a light-colored volcanic rock containing lots of bubbles from trapped gases.

BASALT - Basalt is a hard, black volcanic rock.

CALDERA - A caldera is a large, usually circular depression at the summit of a volcano formed when magma is withdrawn or erupted from a shallow underground magma reservoir.

ERUPTION CLOUD - A cloud of tephra and gases that forms downwind of an erupting volcano is called an eruption cloud.

FAULT - Faults are fractures or fracture zones in the Earth's crust along which one side moves with respect to the other. A fault scarp is a cliff or steep slope that sometimes forms along the fault at the surface.

FISSURE - On volcanoes, a fissure is an elongate fracture or crack at the surface from which lava erupts.

PILLOW LAVA - When basalts erupt underwater, they commonly form pillow lavas, which are mounds of elongate lava "pillows" formed by repeated oozing and quenching of the hot basalt.

PRYOCLASTIC FLOW - A pyroclastic flow is a ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas that rushes down the side of a volcano.

TEPHRA - Tephra is a general term for fragments of volcanic rock and lava regardless of size that are blasted into the air by explosions or carried upward by hot gases in eruption columns or lava fountains.

VENT - Vents are openings in the Earth's crust from which molten rock and volcanic gases escape onto the ground or into the atmosphere.

OBSIDIAN - Obsidian is dense volcanic glass, usually rhyolite in composition and typically black in color.

Click Here to see if there has been any recent volcanic activity across the U.S.

PLAN FOR A VOLCANO: First of all, have a disaster plan and know whether or not you are at risk for danger. Be prepared for mudslides, flash floods, earthquakes, ash falling, acid rain and tsunamis. Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing, dust mask, goggles and sturdy shoes. Don't forget, know all of your evacuation routes.

DURING A VOLCANO: Follow the evacuation order issued by authorities. Avoid areas downwind and river valleys downstream of the volcano. If your caught indoors, close all windows and doors, put machinery inside a barn, and bring animals inside. If you're trapped outdoors, seek shelter indoors. If you're caught in falling rocks, roll into a ball and protect your head. If you're caught near a stream, be aware of mudflows and move to higher ground. Protect yourself when ash falls by wearing long-sleeved shirts and long pants. Use goggles to protect your eyes. Wear a dust mask and keep car engines off.

AFTER A VOLCANO: Cover you mouth and nose. Volcanic ash can irritate your respiratory system. Wear goggles and protect your eyes. Keep your skin covered. Clear roofs of ash, because the ash is very heavy and can cause the building to collapse.

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What is a volcano? A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. Gases and rock shoot up through the opening and spill over or fill the air with lava fragments.

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A volcano is an opening in the Earth's crust that allows molten rock, gases, and debris to escape to the surface.

A volcanic eruption may release acid, gases, rocks, and ash into the air. Lava and debris can flow at up to 100 miles per hour, destroying everything in their path. About 11 percent of the world's active volcanoes are located in the U.S., which has approximately 170 volcanoes. These volcanoes are both active and dormant. Earthquakes, flash floods, landslides, debris and mudflow (lahar), or acid rain may happen at the same time as a volcanic eruption.

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Kids can learn volcano facts, as well as if they’re at risk of experiencing a volcano and what they can do to prepare.

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When magma finds a way to escape from beneath the earth’s surface, it creates a volcano.

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Kids learn about the science of volcanoes including how they form mountains, lava, and magma; types such as cinder cone, composite, and shield; watch a video about volcanoes.

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What is a Volcano?

A volcano is a landform (usually a mountain) where molten rock erupts through the surface of the planet.

In simple terms a volcano is a mountain that opens downward to a pool of molten rock ( magma) below the surface of the earth. It is a hole in the Earth from which molten rock and gas erupt.

Did you know?

What is the difference between lava and Magma?

Magma is liquid rock inside a volcano.

Lava is liquid rock (magma) that flows out of a volcano. Fresh lava ranges from 1,300° to 2,200° F (700° to 1,200° C) in temperature and glows red hot to white hot as it flows.

How many volcanoes are there in the world?

There are around 1,510 active volcanoes in the world.

We currently know of 80 or more which are under the oceans.

What are the three layers the Earth is made of?

Crust
The crust is the outer layer of Earth. It is about 18 miles thick. It is the part we live on.

Mantle
The second layer is called the mantle. It is about 1,800 miles thick.

Core
The inner layer is called the core.

What causes volcanoes to erupt?

The Earth's crust is made up of huge slabs called plates, which fit together like a jigsaw puzzle. These plates sometimes move.

Between the Earth's crust and the mantle is a substance called magma which is made of rock and gases.

When two plates collide, one section slides on top of the other, the one beneath is pushed down. Magma is squeezed up between two plates.

Did you know?

When magma erupts, what is it called?

When magma erupts through the earth's surface it is called lava

What is the Ring of Fire?

Over half of the world's volcanoes arise in a belt around the Pacific Ocean called the Ring of Fire.

Volcano Eruptions
Largest active volcano Websites
Volcanoes around the World
Each triangle on the map represents a volcano.

Volcano FAQ's -- Learn About Volcanoes
What is a volcano? ... Why do volcanoes erupt? ... Where do volcanoes erupt? ... How hot is a volcano?

Information on Volcanoes including volcanoes and climate

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Facts and information on Mountains for kids, including the five different types of mountains that exist.

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64 Interesting Facts about Volcanos | FactRetriever.com

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Named after the Roman god of fire, Vulcan, volcanoes are known for their awesome power. Explore fun volcano facts to learn why they are so crucial to life.

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Your chances of being involved in a volcanic eruption are pretty low compared to other natural disasters, such as flooding or earthquakes. Still, it's good to know what to watch for and what to do. Volcanoes are like giant vents for the Earth.

Imagine a pot of chili bubbling on the stove. If it has a lid on it, steam can't escape. The chili might just bubble up and erupt over the sides of the pan. Take the lid off, though, and the heat can escape.

Deep under the earth's crust is magma - rock that is so hot that it is a liquid. Along with this rock are explosive gases. The earth's crust is not one solid piece, but many pieces that fit together like a puzzle.

When these pieces rub up against each other, they create pressure. Magma and gases build up. Finally, they explode through holes or vents in the earth's surface. As the magma, or lava, cools and hardens, it forms mountains over millions of years. These mountains are known as volcanoes.

Volcanoes are fascinating and terrifying. They spew lava, rock, poisonous gases and ash with great power. Lava is much, much hotter than any oven -over 2000 degrees Fahrenheit. As it pours out of the Earth, it can burn anything in its path. Poisonous gases and ash can cause serious illness or death.

Volcanoes F acts for Kids

There are about 1,900 active volcanoes on the earth. This means they have erupted recently or they might erupt. Some volcanoes are extinct. Over 80 volcanoes have been found in the ocean.

Most volcanoes happen on fault lines, or cracks in the Earth's surface.

There are three different types of volcanoes - Strato (Composite), Shield (these are the largest volcanoes) and Dome.

A volcano has three categories to fall under: Extinct (was a volcano but will never erupt again or is not expected), Dormant (has not erupted in thousands of years but is likely to erupt again), Active (has the potential to erupt at any stage or has erupted since the last ice age).

Most of the earth's volcanoes are in the Pacific Ocean, in an area called the Ring of Fire.

The word "volcano" comes from Vulcan, the Roman god of fire.

Lava from volcanoes can reach temperatures of 2,000 degrees Fahrenheit.

Volcanoes spew out ash and toxic gases, as well as lava and lava boulders.

Pompeii was an ancient city that was completely buried in ash and lava.

Mauna Loa in Hawaii (Pacific Ocean) is the world's largest active shield volcano standing at 4,170 m high. Mauna Kea also in Hawaii is a taller volcano with a height of 4,207 m but currently is dormant. Mauna has not erupted since 2460 BC.

Mount Etna in Sicily (Italy) is Europe's largest active volcano at 3,329 m high.

Mount Damavand a stratovolcano in Iran is the largest volcano in Asia standing at 5,610 m.

Mount Erebus is the largest active volcano in Antarctica with its peak reaching 3,794.

Indonesia has the most active volcanoes in the world and remains one of the most dangerous areas.

10% of the earth's active volcanoes can be found in Japan.

Over 20% of the earth's active volcanoes are underwater.

The volcanic pumice rock is the only known rock that can float in water.

Volcano Vocabulary

Cool Video for Kids on Volcanoes

Watch this Science Video to Learn More All About Volcanoes:

This is a video explaining about volcanic eruptions.

Question: Are there any benefits to volcanoes?

Answer: Volcanoes relieve pressure inside the earth, similar to when you lift the lid on a pot of simmering food. Soils around old lava fields are often fertile and grow good crops.

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Question: Are all volcanoes mountains?

Answer: Sometimes volcanoes can be plateaus or even cracks in the ground.

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Question: How serious are volcanoes to people?

Answer: Most volcanoes occur where few people live, but when a volcano actively erupts, it can be very dangerous to anyone living nearby. Over 260,000 people have died in volcanoes in the last 300 years. Many people live in the valley beneath Mt. Rainier, the most dangerous volcano in America. The volcano isn't likely to erupt, but dangerous mudslides called Iahars roar down its peaks.

Enjoyed the Natural Science for Kids website all about Volcanoes info? Take the FREE & fun all about Volcanoes quiz and download FREE Volcanoes worksheet for kids. For lengthy info click here.

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Your chances of being involved in a volcanic eruption are pretty low compared to other natural disasters, such as flooding or earthquakes. Still, it's good to know what to watch for and what to do. Volcanoes are like giant vents for the Earth. Imagine a pot of chili bubbling on the stove.

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Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes. But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish.

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those-over 10 percent-sit within the boundaries of the United States.

But each volcano is different. Some burst to life in explosive eruptions, like the 1991 eruption of Mount Pinatubo, and others burp rivers of lava in what's known as an effusive eruption, like the 2018 activity of Hawaii's Kilauea volcano. These differences are all thanks to the chemistry driving the molten activity. Effusive eruptions are more common when the magma is less viscous, or runny, which allows gas to escape and the magma to flow down the volcano's slopes. Explosive eruptions, however, happen when viscous molten rock traps the gasses, building pressure until it violently breaks free.

How do volcanoes form?

The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates-massive expanses of our planet's lithosphere that continually shift, bumping into one another. When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone.

As the descending landmass sinks deep into the Earth, temperatures and pressures climb, releasing water from the rocks. The water slightly reduces the melting point of the overlying rock, forming magma that can work its way to the surface-the spark of life to reawaken a slumbering volcano.

Not all volcanoes are related to subduction, however. Another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity-or a hotspot-in the middle of a tectonic plate can push up through the crust to form a volcano. Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface. This mechanism is thought to be behind the Hawaii volcanic chain.

Where are all these volcanoes?

Some 75 percent of the world's active volcanoes are positioned around the ring of fire, a 25,000-mile long, horseshoe-shaped zone that stretches from the southern tip of South America across the West Coast of North America, through the Bering Sea to Japan, and on to New Zealand.

This region is where the edges of the Pacific and Nazca plates butt up against an array of other tectonic plates. Importantly, however, the volcanoes of the ring aren't geologically connected. In other words, a volcanic eruption in Indonesia is not related to one in Alaska, and it could not stir the infamous Yellowstone supervolcano.

What are some of the dangers from a volcano?

Volcanic eruptions pose many dangers aside from lava flows. It's important to heed local authorities' advice during active eruptions and evacuate regions when necessary.

One particular danger is pyroclastic flows, avalanches of hot rocks, ash, and toxic gas that race down slopes at speeds as high as 450 miles an hour. Such an event was responsible for wiping out the people of Pompeii and Herculaneum after Mount Vesuvius erupted in A.D. 79.

Similarly, volcanic mudflows called lahars can be very destructive. These fast-flowing waves of mud and debris can race down a volcano's flanks, burying entire towns.

Ash is another volcanic danger. Unlike the soft, fluffy bits of charred wood left after a campfire, volcanic ash is made of sharp fragments of rocks and volcanic glass each less than two millimeters across. The ash forms as the gasses within rising magma expand, shattering the cooling rocks as they burst from the volcano's mouth. It's not only dangerous to inhale, it's heavy and builds up quickly. Volcanic ash can collapse weak structures, cause power outages, and is a challenge to shovel away post-eruption.

Can we predict volcanic eruptions?

Volcanoes give some warning of pending eruption, making it vital for scientists to closely monitor any volcanoes near large population centers. Warning signs include small earthquakes, swelling or bulging of the volcano's sides, and increased emission of gasses from its vents. None of those signs necessarily mean an eruption is imminent, but they can help scientists evaluate the state of the volcano when magma is building.

However, it's impossible to say exactly when, or even if, any given volcano will erupt. Volcanoes don't run on a timetable like a train. This means it's impossible for one to be "overdue" for eruption -no matter what news headlines say.

What is the largest eruption in history?

The deadliest eruption in recorded history was the 1815 explosion of Mount Tabora in Indonesia. The blast was one of the most powerful ever documented and created a caldera -essentially a crater-4 miles across and more than 3,600 feet deep. A superheated plume of hot ash and gas shot 28 miles into the sky, producing numerous pyroclastic flows when it collapsed.

The eruption and its immediate dangers killed around 10,000 people. But that wasn't its only impact. The volcanic ash and gas injected into the atmosphere obscured the sun and increased the reflectivity of Earth, cooling its surface and causing what's known as the year without a summer. Starvation and disease during this time killed some 82,000 more people, and the gloomy conditions are often credited as the inspiration for gothic horror tales, such as Mary Shelley's Frankenstein.

Although there have been several big eruptions in recorded history, volcanic eruptions today are no more frequent than there were a decade or even a century ago. At least a dozen volcanoes erupt on any given day. As monitoring capacity for-and interest in-volcanic eruptions increases, coverage of the activity more frequently appears in the news and on social media. As Erik Klemetti, associate professor of geosciences at Denison University, writes in The Washington Post: "The world is not more volcanically active, we're just more volcanically aware."

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Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes.

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Biggest recorded

The biggest volcanic eruption ever recorded by humans was the explosion of Mount Tambora on Sumbawa Island, Indonesia, in 1815. It ranked a 7 (or "super-colossal") on the Volcanic Explosivity Index, the second-highest rating in the index.

Long-lasting effects

The gas and other particles spewed high into the atmosphere during the 1991 eruption of Mount Pinatubo reduced global temperatures by about 0.9 degrees Fahrenheit (0.5 degrees Celsius) during the following year.

Lots of ash

The 1991 eruption of Mount Pinatubo ejected more than 1 cubic mile (5 cubic kilometers) of material into the air and created a column of ash that rose 22 miles (35 km) in the atmosphere.

Big blast

The largest volcanic blast of the 20th century was the eruption of Novarupta one of a chain of volcanoes on the Alaska Peninsula, part of the Pacific Ring of Fire in 1912. It was a 6 (out of a possible 8) on the Volcanic Explosivity Index.

Continuous erupting

Hawaii's Kilauea volcano, one of the most active on Earth, has been erupting continuously for more than 29 years, beginning Jan. 3, 1983.

Deadly eruption

Kilauea erupted 200 years ago, sending speeding lava flows down its peaks and killing more than 400 people, including Hawaiian warriors. It was the deadliest volcanic eruption on record in what is now the United States.

Far-reaching effect

Kilauea means "spewing" or "much spreading" in Hawaiian.

New activity

More than 90 percent of Kilauea's surface is covered by lava less than 1,100 years old.

Stratovolcanoes

Stratovolcanoes are tall, steep, conical structures that periodically erupt explosively and are commonly found where one of Earth's plates is subducting below another, producing magma along a particular zone.

Large mountains

The Hawaiian shield volcanoes are the largest mountains on Earth. The total height of Mauna Kea, below and above sea level, is 33,500 feet (10,210 meters), making it taller than even Mount Everest.

Largest volcanoes

The largest volcanoes on Earth are shield volcanoes, which have broad, gentle slopes built by fluid basalt lavas.

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The biggest volcanic eruption ever recorded by humans was the explosion of Mount Tambora on Sumbawa Island, Indonesia, in 1815. It ranked a 7 (or "super-colossal") on the Volcanic Explosivity Index, the second-highest rating in the index.

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Enjoy our awesome range of Earth facts for kids. Check out the cool trivia and have fun learning about some of our planet's most amazing features.

Fun Volcano Facts

Check out these fun volcano facts for kids. Learn about hot magma, famous eruptions, volcanoes on other planets, volcanic gases, flowing lava and more. Enjoy our wide range of strange and interesting facts about volcanoes.

Volcanoes are openings in the Earth's surface. When they are active they can let ash, gas and hot magma escape in sometimes violent and spectacular eruptions.

The word volcano originally comes from the name of the Roman god of fire, Vulcan.

Volcanoes are usually located where tectonic plates meet. This is especially true for the Pacific Ring of Fire, an area around the Pacific Ocean where over 75% of the volcanoes on Earth are found.

While most volcanoes form near tectonic boundaries, they can also form in areas that contain abnormally hot rock inside the Earth. Known as mantle plumes, these hotspots are found at a number of locations around the globe with the most notable being in Hawaii.

Hot liquid rock under the Earth's surface is known as magma, it is called lava after it comes out of a volcano.

Some famous volcanic eruptions of modern times include Mount Krakatoa in 1883, Novarupta in 1912, Mount St Helens in 1980 and Mt Pinatubo in 1991.

While we certainly have some big volcanoes here on Earth, the biggest known volcano in our solar system is actually on Mars. Its name is Olympus Mons and it measures a whooping 600km (373 miles) wide and 21km (13 miles) high.

The object with the most volcanic activity in our solar system is Io, one of Jupiter's moons. Covered in volcanoes, its surface is constantly changing to the large amount of volcanic activity.

Most people think of volcanoes as large cone shaped mountains but that is just one type, others feature wide plateaus, fissure vents (cracks were lava emerges) and bulging dome shapes.

There are also volcanoes found on the ocean floor and even under icecaps, such as those found in Iceland.

Volcanoes can be active (regular activity), dormant (recent historical activity but now quiet) or extinct (no activity in historical times and unlikely to erupt again). While these terms are useful, scientists are more likely to describe volcanoes by characteristics such a how they formed, how they erupt and what their shape is.

Common volcanic gases include water vapor, carbon dioxide, sulfur dioxide, hydrogen chloride, hydrogen fluoride and hydrogen sulfide.

Volcanic eruptions can send ash high into the air, over 30km (17 miles) above the Earth's surface.

Large volcanic eruptions can reflect radiation from the Sun and drop average temperatures on Earth by around half a degree. There have been several examples of this over the last century.

Pumice is a unique volcanic rock ( igneous) that can float in water. It can also be used as an abrasive and is sometimes used in beauty salons for removing dry skin.

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Fun Volcano Facts for Kids - Interesting Facts about Volcanoes

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Enjoy our awesome range of Earth facts for kids. Check out the cool trivia and have fun learning about some of our planet's most amazing features. Fun Volcano Facts Check out these fun volcano facts for kids. Learn about hot magma, famous eruptions, volcanoes on other planets, volcanic gases, flowing lava and more.

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Wildfires

What is a wildfire?
A wildfire also known as a wildland fire, forest fire, vegetation fire, grass fire, peat fire, bushfire (in Australia), or hill fire is an uncontrolled fire often occurring in wildland areas, but which can also consume houses or agricultural resources. Wildfires often begin unnoticed, but they spread quickly igniting brush, trees and homes.

What causes a wildfire?

Common causes of wildfires include lightning, human carelessness, arson, volcano eruption, and pyroclastic cloud from active volcano. Heat waves, droughts, and cyclical climate changes such as El Niño can also have a dramatic effect on the risk of wildfires. Although, more than four out of every five wildfires are caused by people.

Where can wildfires occur?
Wildfires can occur anywhere, but are common in the forested areas of the United States and Canada. They are also susceptible in many places around the world, including much of the vegetated areas of Australia as well as in the Western Cape of South Africa. The climates are sufficiently moist to allow the growth of trees, but feature extended dry, hot periods. Fires are particularly prevalent in the summer and fall, and during droughts when fallen branches, leaves, and other material can dry out and become highly flammable. Wildfires are also common in grasslands and scrublands.
What are the Santa Ana winds?

The Santa Ana winds are hot, dry winds that aggravate the fire danger in forests and bush lands. These winds characteristically appear in Southern California and Northern Baja California weather during autumn and early winter. In southern California, under the influence of Santa Ana winds, wildfires can move at tremendous speeds, up to 40 miles in a single day, consuming up to 1,000 acres per hour. Dense clouds of burning embers push ahead of the flames crossing firebreaks without a problem.

What is a fire tornado?

A fire tornado or fire whirl is just a tornado made of fire. It happens when certain conditions (depending on air temperature and currents), acquires a vertical vorticity and forms a whirl, or a tornado-like effect. Fire tornadoes may be whirlwinds separated from the flames, either within the burn area or outside it. A fire tornado can make fires more dangerous.

How do firefighters put out the wildfires?
Firefighters use a tool known as a pulaski. Its a combination of an ax and hoe used to dig a fireline. A fireline is a strip of land from which all brush and debris have been cleared to rob a wildfire of its fuel. Firefighters also use hotshots and smoke jumpers to clear a large path in a big circle around the fire so the blaze is contained in a ring of dirt. When the fire reaches this area, it runs out of fuel and starves to death. If the fire is too large, however, planes and helicopters fly overhead, dropping water and special chemicals that smother the flames. This pink, fire-retardant chemical is called sky jell-o.

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Know the Lingo

SURFACE FIRES - The most common type of wildfires, surface fires move slowly and burn along the forest floor, killing and damaging vegetation.

GROUND FIRES - These are usually started by lightning, ground fires burn on or below the forest floor through the root system.

CROWN FIRES - These fires spread by wind moving quickly along the tops of trees.

SANTA ANA WINDS - "Santa Ana" is the name given to the gusty northeast or east wind that occurs in Southern California during the fall and winter months. Santa Ana winds are often hot and very dry, greatly aggravating the fire danger in forests and bush lands.

CONFLAGRATION - A large and destructive fire, typically aggravated by strong winds that carry firebrands over natural or artificial barriers.

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Wildfire Safety Tips
BEFORE A WILDFIRE: Have a disaster plan. Know whether you're in a wildfire prone area. Plant fire resistant shrubs and trees around your home. Have a garden hose that is long enough to reach around your home. Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water. Always listen to the radio and television for the latest information and instructions for your area.
DURING A WILDFIRE: If you're advised to evacuate then do so immediately. Wear protective clothing and lock your home. Tell someone you left and where you are going. Choose a safe route away from fire hazards. Watch for changes in the speed and direction of fire and smoke.

AFTER A WILDFIRE: Stay away from wildfire areas until it is safe.
Wildfire Activities
Lesson Plan: Here is a great lesson plan on teaching students to have an escape plan if a fire threatens their home.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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Weather Wiz Kids weather information for kids

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Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

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Have you ever heard of a fire triangle? Wildfires need three things to thrive and firefighters call these three things the fire triangle. They include a fuel source, such as dry wood and plants; oxygen, which is delivered by wind and air; and a heat source, such as a cigarette, a spark from a campfire, a lightning strike or even the sun.

Every year in the U.S., wildfires burn more than 5 million acres. Wildfires can start in a second and move at about 14 miles per hour.

Facts about Wildfires for Kids

Most wildfires are caused by humans, but some fires are caused by nature.

Wildfires can destroy homes and buildings and even kill people.

In some ways, wildfires are good, though. They clear dead and diseased plants so new plants can grow.

Firefighters sometimes fight wildfires from planes or helicopters. They drop water or fire-retardant chemicals on or near the fire.

Firefighters also fight wildfires by cutting back brush and grass.

In August 2018 California suffered the largest wildfire in the history of the state.

In the event of a wildfire it is important to be prepared. Call 911 and take the advice of the authorities. If an order is made to leave the area, do so immediately. Leave all personnel belongings, you can replace them.

Fill bathtubs and sinks with water and stay indoors with windows and doors closed but unlocked.

Keep away from windows.

If you happen to be caught outside in a wildfire keep low, try find a ditch and lie face down in it, covering your body. Try find an area clear from vegetation like trees and bushes.

If you happen to be in your vehicle, close the vents and windows. Lie on the floor again covering your body. If you can find an area free from vegetation its safer, stay there, do not panic. It is very easy to become disorientated in a wildfire, so driving around unsure where you are going will only put you in more danger.

Visit this government website and be prepared https://www.ready.gov/wildfires

Wildfires Vocabulary

Learn More All About Wildfires

This is the best video we found for kids to learn about Wildfires:

This is a video animation about preventing wildfires.

Wildfires Q&A

Question : What can I do to prevent wildfires?

Answer: Most wildfires happen during the heat of summer in dry, western states, such as Utah, Idaho, California and Colorado. If you live in one of these states, follow local rules about fires and fireworks. Be extra careful with campfires.

Enjoyed the Free Geography Kids online resources all about Wildfires info? Take the FREE & fun all about Wildfires quiz and download FREE all about Wildfires worksheet for kids. For lengthy info click here.

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Have you ever heard of a fire triangle? Wildfires need three things to thrive and firefighters call these three things the fire triangle. They include a fuel source, such as dry wood and plants; oxygen, which is delivered by wind and air; and a heat source, such as a cigarette, a spark from a campfire, a lightning strike or even the sun.

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Kids can learn wildfire facts, as well as if they’re at risk of experiencing a wildfire and what they can do to prepare.

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Kids learn about forest fires including major human and natural causes, how they spread, firefighters, campfire safety, fun facts, and good wildfires.