# data[].attributes.body
Tsunamis are ocean waves triggered by large earthquakes that occur near or under the ocean, volcanic eruptions, submarine landslides, and by onshore landslides in which large volumes of debris fall into the water. Scientists do not use the term "tidal wave" because these waves are not caused by tides. Tsunami waves are unlike typical ocean waves generated by wind and storms, and most tsunamis do not "break" like the curling, wind-generated waves popular with surfers. Tsunamis typically consist of multiple waves that rush ashore like a fast-rising tide with powerful currents. Tsunami waves can travel much farther inland than normal waves.

# data[].attributes.body
Click "View All Hazards" on the Weather Wall to get to the Disaster Alert Map.

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.description
Tsunamis are giant, powerful waves most often caused by earthquakes beneath the ocean floor. Their incredible power can destroy entire communities, then drag the debris out to sea. This video shows what causes tsunamis and the importance of evacuating any area under a tsunami alert.

# data[].attributes.body
Source: adobe.stock.com

# data[].attributes.body
Earthquakes are formed as the tectonic plates that make up the crust of the earth rub against each other. While approximately 8,000 earthquakes occur every day worldwide, nearly all are too small to feel. Occasionally one is large and close enough to a populated area it can create significant damage. Engineers design devices such as seismometers and lasers that can help predict earthquakes through the data they collect. Engineers take into consideration the powerful forces of earthquakes when designing structures and bridges.

# data[].attributes.body
A wildfire is an unplanned fire that burns in a natural area such as a forest, grassland, or prairie. Wildfires can ruin homes and cause injuries or death to people and animals.

# data[].attributes.attachment_link.title
What causes a wildfire? | Natural Disasters

# data[].attributes.body
Forest fires are natural hazards that can be tremendously destructive. Forest fires occur in heavily forested areas during the dry season. They are usually started by lightning or human activities such as campfires. Periodic forest fires are good for the forest because they help to thin the forest and allow for new growth. Forest fires also have the potential to destroy houses and towns in or near forested areas. To minimize the impact of forest fires, engineers design tractors that cut and clear fire lanes (forest strips in which all vegetation is removed) to halt the spread of a forest fire. Engineers also design aircraft that drop water or chemical retardants on fires.

# data[].attributes.attachment_link.readable_text
For the fire triangle to stand, all three ingredients must be present. If the heat is not enough, or the fuel runs out, or the oxygen runs out, the fire will be out. Fuel:Fuel is any kind of combustible material. This can be gas, liquids or solids. Examples of solid fuels include wood, dry leaves and even paper. Examples of liquid fuels include petro and turpentine. Examples of gas fuels include LPG Gas. Fuels with less moisture tend to burn faster than fuels with high moisture.

Introduction to wildfires

Out of the many natural disasters we have, wild fires would be one that is very common, very difficult to fight, and maybe the most dangerous.

Simple, it is the visible part of a combustion. A combustion is a chemical reaction of three things:Heat, fuel and Oxygen. These three ingredients must be present before a fire can be made and maintained.

This can be best explained in the fire triangle below.

What is a fire?

Oxygen:
This is simply a gas found in air. The air we breath contains about 21% of oxygen. In fact, only 16% is all that is needed to produce fire. When fuel burns, it reacts with oxygen from the surrounding air. This chemical reaction releases heat and other products such as gases, smoke and particles. This process is known asoxidation. This is why some smoke can be very dangerous because depending on what is burning, the gases produced can be very deadly.

Heat is thermal energy. You may not see it, but can feel it. Extreme heat of about 617°F will start a fire in the presence of fuel and oxygen. Heat eliminates moisture from any nearby fuel, warms the air around and prepares the fire path to accept the fire and make it burn with ease.

Heat:

# data[].attributes.attachment_link.title
Information on wildfires for young people

# data[].attributes.attachment_link.description
For the fire triangle to stand, all three ingredients must be present. If the heat is not enough, or the fuel runs out, or the oxygen runs out, the fire will be out. Fuel:Fuel is any kind of combustible material. This can be gas, liquids or solids.

# data[].attributes.attachment_link.description
Explore National Geographic. A world leader in geography, cartography and exploration.

# data[].attributes.attachment_link.readable_text
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.

Click Here to get the latest wildfire information.

Click Here for to get more wildfire information.

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

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.

Click Here to learn about more wildfire facts!

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.

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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.authors[].name
National Institute of Standards and Technology

# data[].attributes.attachment_link.readable_text
Forest fires are large uncontrolled fires that take place in the forest. Some of the fiercest fires occur in the forest because there is so much fuel (trees) to burn. Forest fires are a type of wildfire. Other types of wildfires include grass fires, brush fires, and hill fires.

Major Causes of Forest Fires

The major cause of forest fires in the United States is human activities. This can be carelessness such as not putting out a campfire or dropping a lit cigarette. It may also be arson, which is setting a fire on purpose and is against the law. Around 80% of forest fires in the United States are caused by humans.

# data[].attributes.attachment_link.description
Kids learn about forest fires including major human and natural causes, how they spread, firefighters, campfire safety, fun facts, and good wildfires.

# data[].attributes.headline
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.subject
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.body
Source: adobe.stock.com

# data[].attributes.attachment_link.readable_text
Wildfires are unplanned fires that burn in natural areas like forests, grasslands or prairies. These dangerous fires spread quickly and can devastate not only wildlife and natural areas, but also communities.

Prepare for Wildfires

Stay Safe During

Returning Home After a Wildfire

Additional Resources

Videos

Social Media & Graphics

More Info

# data[].attributes.attachment_link.description
How to prepare for a wildfire, stay safe during a wildfire, and return home safely after a wildfire. Prepare for Wildfires Stay Safe During After a Wildfire Additional Resources Wildfires are unplanned fires that burn in natural areas like forests, grasslands or prairies.

# data[].attributes.attachment_link.title
What causes an earthquake? | Natural Disasters

# data[].attributes.attachment_link.readable_text
Earthquakes and Tsunamis... Did you know?

Scientists can locate the epicenter of an earthquake by studying the different speeds of seismic waves.

In modern architecture and engineering, buildings can be constructed to be earthquake-proof. They are built to sway and stand after the waves run through the earth's surface. This is particularly useful in areas know to be earthquake-prone. Even if they fall, there will be less damage to life and property.

The world's earliest recorded earthquake occurred on January 23, 1556, in Shaanxi, Central China. It had a magnitude of 8.0, and an estimated 830 people were killed. Many people there lived in caves dug into soft rock and these collapsed during the earthquake.

Himalaya-Karakoram is believed to have been created y the movement of Tectonic plates. This land mountain range is the greatest in the world. It has 96 of the world's 109 peaks of over 7,317m (24,000 ft approx), with the longest range in the Andes of South America, which is 7,564km (4700 mi) in length.

The largest recorded earthquake in the world was a magnitude 9.5 (Mw) in Chile on May 22, 1960.

The East African Rift System is a 31-37 miles wide zone of active volcanoes and faulting that extends north-south in eastern Africa for more than 3000 km (1864 miles) from Ethiopia in the north to the Zambezi in the south. It is a rare example of an active continental rift zone, where a continental plate is attempting to split into two plates which are moving away from one another. earthquake.usgs.gov

Faults were first recognized as the source of earthquakes in 1855. Before that, the first "pendulum seismoscope" was developed in 1751 to measure the shaking of the ground during an earthquake.

A tsunami and a tidal wave are two different things. A tidal wave is caused by the earth's movement and interactions between the sun and the moon. It is usually very shallow water and very mild. A tsunami is a sea wave caused by an underwater earthquake or landslide. It is usually triggered by an earthquake and results in displacing the ocean water, throwing it ashore and into the land.

# data[].attributes.attachment_link.title
Earthquakes and Tsunamis... Did you know?

# data[].attributes.attachment_link.description
Earthquakes and Tsunamis... Did you know? Scientists can locate the epicenter of an earthquake by studying the different speeds of seismic waves. In modern architecture and engineering, buildings can be constructed to be earthquake-proof. They are built to sway and stand after the waves run through the earth's surface.

# data[].attributes.body
Floods are natural hazards that involve an overflow of water that submerges usually dry land. Of the many different types and causes of floods, the most common are periodic river flooding and flash flooding. Periodic river flooding is caused by melting snow and spring rain increasing a river's water level. Flash floods occur when water from rainstorms is suddenly too much for streams and rivers to contain. Engineers design river gauges and weather monitoring devices that take measurements that help us predict and monitor floods. They also design dams and levees to prevent and minimize flooding.

# data[].attributes.attachment_link.readable_text
Rain is pouring hard and fast-more than eight inches in just an hour, turning river water brown with mud. Earthworms wiggle up to the ground as the soil becomes too wet for them. A flood might be coming.

Just about any place on Earth can experience flooding. When so much rain falls that the ground can't absorb it or waterways can't hold it, the overflowing water becomes a destructive force. In the United States, flooding causes more death and damage than tornadoes, hurricanes, or lightning.

How floods develop

During a rainstorm, precipitation-or the water that comes from rain or snow-goes to different places. Some of it flows into streams, lakes, or city water systems. Other precipitation evaporates and returns to the atmosphere.

But much of the rainwater is absorbed by soil. It flows through the top layer of the ground, to plant roots below the surface. This helps provides plants with the water and nutrients they need to grow. The excess water moves deeper into the ground through layers of dirt and rocks where until it becomes part of natural underground wells called groundwater.

A habitat can naturally absorb a healthy amount of rainfall it needs to thrive. But too much rain can cause lake and river levels to rise and overflow their banks, or the soil to become too wet to absorb more water. And though you might think extremely dry habitats would welcome too much rain, it turns out that the parched dirt can't absorb the rain fast enough to capture it all.

Severe coastal storms, quickly melting ice and snow, and collapsed barriers (like concrete dams) can also cause floods. Even damaged beaver dams can lead to an overflow of water that the surrounding earth can't absorb.

Different types of floods

Floods can form slowly over several days or overwhelm an area with little warning. How quickly a flood forms often depends on the habitat.

Slow-forming river flooding happens in regions called floodplains. These are large, flat areas of land along waterways with very shallow banks. When big storms hit, the water overflows the banks and spreads out across the plains.

This type of flooding isn't always bad. It brings nutrients to the surrounding soil, making it fertile for growing crops. That's why many people live in or near floodplains.

But too much water can destroy crops and damage homes. Rushing water can disrupt ecosystems by moving aquatic plants and animals to other habitats. And if flooding is so severe that it flows into local water treatment facilities, experts must monitor the incoming water to make sure the water is safe.

Another type of flooding is called a flash flood, when a flood happens within six hours of a heavy rainfall-as much as eight inches an hour. With no place to go, the moving water will tear through highways, valleys, and canyons, washing away vehicles, roads, bridges, and houses.

Quickly melting ice and snow can also cause flash flooding, especially when mountain snowmelt overflows the waterways below. On coastlines, hurricane rains cause water levels to rise, and the high winds push that water onto land. Called a storm surge, this also causes flash flooding.

Flooding in the future

Scientists believe that warming temperatures caused by climate change are increasing the risk of floods all over the world, especially in coastal and low-lying areas.

Warmer water changes the patterns of ocean currents, which changes global weather patterns. This means that some places will receive more rainfall than the ground can absorb. Other places will get less rain so the land will be drier-and unable to handle rainfall when it does occur.

Scientists think that climate change could also cause stronger hurricanes, with more rain and higher winds causing bigger storm surges. A warmer climate could also mean more snowmelt overwhelming the soil; melting polar ice could cause sea levels to rise and increase flooding. ( Find out how you can help slow climate change.)

How to survive a flood

Experts might issue a flash flood watch if weather conditions are right. It doesn't mean flooding will happen but that meteorologists want people to be prepared. When experts are sure a flash flood is on the way, they issue a warning so people can evacuate immediately. Here's how to keep you and your family safe.

Before a flood
* Know your neighborhood. Research how close you are to streams, drainage channels, canyons, and any other low-lying areas that might flood.
* Keep emergency contact phone numbers in one place so you can get in touch with family members.
* Put together an evacuation plan and share it with everyone in your household. Know what paths and routes you can use to quickly get to a high, dry place.
* Conduct flood drills to practice evacuating quickly.
* Maintain an emergency kit with a three-day supply of food and water. Experts recommend canned or dried foods that don't need to be cooked, and at least one gallon of water per day for each person and pet.

During a flood
* Never wait for orders to leave; if you think a flood might be coming, evacuate immediately.
* If flooding hasn't started, move important items to upper floors of your house.
* If flooding has already started where you are, move to the highest place you can find, like a roof of a house or car. Bring as much food, water, and sheltering blankets as possible.
* Never walk through flood water, especially if it's moving. Hazardous chemicals, sewage, and even wild animals are often in floodwater, and just six inches of moving water can knock you off your feet.
* If you must walk through water to escape, walk where the water is still. Never touch electrical equipment if you are standing in water, or even if you're wet.
* If water is quickly rising while you're in your car, leave your vehicle and move to higher ground, like a hill or bridge.

After a flood
* If you've evacuated your house, return only after you're given the all-clear from officials.
* If you stayed put, check your house for damage to electrical systems and appliances. Get rid of any food that might be contaminated from floodwater (or because it's been unrefrigerated for awhile).
* Check your home for wild animals, especially snakes. They can get washed into your home with the floodwater.
* Ask an adult before you use water to brush your teeth, make food, or even wash your hands. Flooding can contaminate water and make you sick.
Learn more about floods at National Geographic.
Flood safety tips from the Nat Geo Kids book Extreme Weather by Thomas Kostigen

# data[].attributes.attachment_link.description
Learn about what causes flooding, different types of floods-and how to stay safe.

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.description
Explore National Geographic. A world leader in geography, cartography and exploration.

# data[].attributes.headline
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.subject
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.body
Source: adobe.stock.com

# data[].attributes.body
Source: emergency.cdc.gov

# data[].attributes.attachment_link.title
What causes a hurricane? | Natural Disasters

# data[].attributes.body
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.

4.0 | Minor Earthquake
5.0 | Moderate Earthquake
6.0 | Strong Earthquake
7.0 | Major Earthquake
8.0 | Great Earthquake

# data[].attributes.body
Source: readyforwildfire.org

# data[].attributes.attachment_link.description
Earthquakes can leave behind incredible devastation, while also creating some of the planet's most magnificent formations. Learn about the geophysics behind earthquakes, how they are measured, and where the most powerful earthquake ever witnessed occurred.

# data[].attributes.attachment_link.description
Explore National Geographic. A world leader in geography, cartography and exploration.

# data[].attributes.headline
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.subject
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.body
Source: wheninmanila.com

# data[].attributes.body
Source: emergency.cdc.gov

# data[].attributes.body
Volcanoes are formed when liquid magma located under the crust of the earth finds a way to the surface. When it reaches the surface it is known as lava. Volcanoes can erupt violently with a huge explosion, spreading lava, ash and rock over a large area. Or, they can erupt more calmly, as when lava oozes out of the ground. Three basic types of volcanoes are shield volcanoes, stratovolcanoes and cinder cones. Shield volcanoes form when lava flows like a liquid creating a low and wide (shield-like) dome. Stratovolcanoes are large, conical-shaped volcanoes formed by layers of deposit from explosive eruptions. Cinder cones are usually smaller and form from the scoria of a single eruption. Scoria is solidified chunks of magma. Engineers create devices such as tiltmeters to monitor mountains so that nearby inhabitants can be warned of impending eruptions.

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.readable_text
Introduction to volcanoes

The earth's mountains, plains, plateaus, soils, rocks, etc. as we see it today is believed to have gone through many phases, with about 80% of it being carved out by the action of volcanoes.

In May 1980, the Mountain St. Helens, in Washington USA , in May 1980, erupted or exploded and it was an awesome natural occurrence because it destroyed some parts of the landscape around it but at the same time it was a beautiful sight.

For history lovers...
In A.D. 79 (really long ago) two Roman cities, Pompeii and Herculaneum, were completely buried in ash and dust in a matter of hours after a volcanic eruption. Their remains were not uncovered until modern archaeology made that discovery 1700 years after. (you can do your own research into this event)

The word, 'volcano' was made out of the name of a Roman god of a small island in the Mediterranean sea of Sicily called 'Volcan'.

Volcanoes occur at weak zones or points in the earth's crust (includingconstructive and destructive boundaries). They do not occur at conservative boundaries. How do Volcanoes look like?
A volcano looks like a mountain, although they are two different things.A mountain is a large natural rise of the earth's surface, more like a giant heap of sand. A volcano is also like a big heap of earth just that this heap is a mixture of lava, ash, dust, and other substances that have piled up over many years. It pours out of an opening in the earth after an eruption. This means volcanic eruptions or explosions can create elevations that we can call mountains.

A volcano is simply a rapture (opening or vent) on the earth's surface (crust) through which molten magma (extremely hot mixture of gases, lava, ash and other burning substances) escape on to the earth's surface.(Bolded words explained here)

Did you know?
The biggest volcano in the world is Mauna Loa in Hawaii. Its whole volume is about 80,000 cubic kilometres.

Now we shall see in a bit more detail how volcanoes come about. Click next.

# data[].attributes.attachment_link.description
Introduction to volcanoes The earth's mountains, plains, plateaus, soils, rocks, etc. as we see it today is believed to have gone through many phases, with about 80% of it being carved out by the action of volcanoes. In May 1980, the Mountain St.

# data[].attributes.attachment_link.readable_text
How Volcanoes Form

In 1980 in Washington, after 123 years of hibernation, Mount St. Helens erupted. The blast destroyed and scorched 230 square miles (370 square kilometers) of forest within minutes. The eruption released an avalanche of hot ash, gas, steam, and rocks that mowed down giant trees up to 15 miles (24 kilometers) away.

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

Volcanoes erupt in different ways. Some, like Mount St. Helens, explode. Explosive eruptions are so powerful, they can shoot particles 20 miles up (32 kilometers), hurl 8-ton boulders more than a half mile (0.8 kilometers) away, and cause massive landslides. Explosive eruptions also create an avalanche of hot volcanic debris, ash, and gas that bulldozes everything in its path. Explosive volcanoes cause most of the volcano-related fatalities.

Volcanoes, like Mauna Loa in Hawaii, are effusive. Rather than a violent explosion, lava pours or flows out. Fatalities from effusive volcanoes are rare because people can usually outrun the lava. However, some people get too close or become trapped with no escape. The flowing lava burns, melts, and destroys everything it touches including farms, houses, and roads.

A volcanic eruption forever changes the landscape. Though volcanoes destroy, they also create mountains, islands, and, eventually, incredibly fertile land.

Carpet of Ash

Volcanic eruptions can cause damage hundreds of miles away. Volcanic ash causes airplane engines to fail, destroys crops, contaminates water, and damages electronics and machinery. The ash carpets the ground, burying everything, sometimes even causing buildings to collapse. Mount St. Helens produced more than 490 tons of ash that fell over a 22,000 square mile (56,980 square kilometer) area and caused problems in cities 370 miles (600 kilometers) away.

# data[].attributes.attachment_link.description
When magma finds a way to escape from beneath the earth's surface, it creates a volcano.

# data[].attributes.attachment_link.readable_text
A volcanic eruption occurs when molten rock, ash and steam pour through a vent in the earth's crust.

Volcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active). Some volcanoes explode. Others are slow-flowing fountains of lava, which is hot fluid rock.

The following are examples of famous volcanic eruptions.

Where: Italy

The eruption of Mount Vesuvius buried the towns of Pompeii and Herculaneum under 20 feet of ash and lava, killing an estimated 20,000 people. The ash that buried the town and the people also preserved them. The work of uncovering the ancient cities began in 1748 and continues to this day.

Where: Indonesia

When: 1883

The greatest explosion in modern times occurred when Krakatoa erupted. The power of the explosion was thought to be 26 times the power of the greatest H bomb, and the roar was heard over one-thirteenth of the surface of the earth. The eruption wiped out 163 villages, killing 36,380 people.

For a list of other volcanic eruptions, see Recent Volcanic Activity and Earthquakes and Volcanic Eruptions at Infoplease.com.

For other information on volcanoes, see also Volcanoes of the World, The Nature of Volcanoes, Principal Types of Volcanoes, Types of Volcanic Eruptions, and Earth's Greatest Volcanic Field.

# data[].attributes.attachment_link.description
A volcanic eruption occurs when molten rock, ash and steam pour through a vent in the earth's crust. Volcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active). Some volcanoes explode. Others are slow-flowing fountains of lava, which is hot fluid rock.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.description
Explore National Geographic. A world leader in geography, cartography and exploration.

# data[].attributes.attachment_link.description
Watch spewing volcanoes, descending lava, and a truck try to escape a lava trap.

# data[].attributes.body
Source: fema.gov

# data[].attributes.attachment_link.description
Hurricanes are the most powerful storms known to man. Find out when hurricane season peaks, how the storms form, and the surprising role they play in the larger global ecosystem.

# data[].attributes.attachment_link.description
Tornadoes are some of the most destructive forces of nature. Learn how tornadoes form, how they are rated, and the country where the most intense tornadoes occur.

# data[].attributes.attachment_link.title
What causes an avalanche? | Natural Disasters

# data[].attributes.attachment_link.title
What causes a landslide? | Natural Disasters

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.body
Listen to this audio recording as you follow along with the text on your paper.

# data[].attributes.headline
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.subject
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.body
Source: venngage.com

# data[].attributes.attachment_link.title
Precautionary Measures for Volcanic Eruption

# data[].attributes.attachment_link.description
Be aware and be alert of the announcements given by the governments *Be Alert! *Be Prepared! *Be Safe! Wear goggles and...

# data[].attributes.body
Listen to this audio recording as you follow along with the text on your paper.

# data[].attributes.body
Listen to this audio recording as you follow along with the text on your paper.

# data[].attributes.body
Listen to this audio recording as you follow along with the text on your paper.

# data[].attributes.body
Hurricane Sandy (also known as Superstorm Sandy) was the most destructive hurricane of the 2012 Atlantic hurricane season. Sandy made landfall in southern New Jersey and became incredible in its size and power. It was a large storm with violent gusts and storm surges that caused major flooding and left millions of people along the East Coast without power. More than 100 people died and tens of thousands of people were injured and relocated. According to NOAA, estimated damage from Sandy is $71 billion, making Sandy the fourth-costliest hurricane in the United State's history, after Hurricanes Katrina, Harvey, and Maria.
(Source: nationalgeographic.com)

# data[].attributes.attachment_link.title
15 Biggest Natural Disasters of 2019 | Worst Natural Disasters of 2019

# data[].attributes.attachment_link.title
The dangers of driving through flood waters

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.readable_text
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.

# data[].attributes.attachment_link.description
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.

# data[].attributes.attachment_link.title
Let's look back at the most intense natural disasters of 2019

# data[].attributes.headline
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.subject
Reducing the Impacts: BEFORE, DURING, AFTER

# data[].attributes.body
Source: fema.gov