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What was Hurricane Katrina?

Who was Hurricane Katrina named after?

What were Hurricane Katrina's wind speeds?

Why did Hurricane Katrina lead to widespread flooding?

What was the impact of Hurricane Katrina on the New Orleans public education system?

Hurricane Katrina, tropical cyclone that struck the southeastern United States in late August 2005. The hurricane and its aftermath claimed more than 1,800 lives, and it ranked as the costliest natural disaster in U.S. history.

Development

The storm that would later become Hurricane Katrina surfaced on August 23, 2005, as a tropical depression over the Bahamas, approximately 350 miles (560 km) east of Miami. Over the next two days the weather system gathered strength, earning the designation Tropical Storm Katrina, and it made landfall between Miami and Fort Lauderdale, Florida, as a category 1 hurricane-a storm that, on the Saffir-Simpson scale, exhibits winds in the range of 74-95 miles (119-154 km) per hour. Sustained winds of 70 miles (115 km) per hour lashed the Florida peninsula, and rainfall totals of 5 inches (13 cm) were reported in some areas. The storm spent less than eight hours over land. It quickly intensified when it reached the warm waters of the Gulf of Mexico.

On August 27 Katrina strengthened to a category 3 hurricane, with top winds exceeding 115 miles (185 km) per hour and a circulation that covered virtually the entire Gulf of Mexico. By the following afternoon Katrina had become one of the most powerful Atlantic storms on record, with winds in excess of 170 miles (275 km) per hour. On the morning of August 29, the storm made landfall as a category 4 hurricane at Plaquemines Parish, Louisiana, approximately 45 miles (70 km) southeast of New Orleans. It continued on a course to the northeast, crossing the Mississippi Sound and making a second landfall later that morning near the mouth of the Pearl River. A storm surge more than 26 feet (8 metres) high slammed into the coastal cities of Gulfport and Biloxi, Mississippi, devastating homes and resorts along the beachfront.

Damage

In New Orleans, where much of the greater metropolitan area is below sea level, federal officials initially believed that the city had "dodged the bullet." While New Orleans had been spared a direct hit by the intense winds of the storm, the true threat was soon apparent. The levee system that held back the waters of Lake Pontchartrain and Lake Borgne had been completely overwhelmed by 10 inches (25 cm) of rain and Katrina's storm surge. Some levees buttressing the Industrial Canal, the 17th Street Canal, and other areas were overtopped by the storm surge, and others were breached after these structures failed outright from the buildup of water pressure behind them. The area east of the Industrial Canal was the first part of the city to flood; by the afternoon of August 29, some 20 percent of the city was underwater.

Disasters of Historic Proportion

New Orleans Mayor Ray Nagin had ordered a mandatory evacuation of the city the previous day, and an estimated 1.2 million people left ahead of the storm. However, tens of thousands of residents could not or would not leave. They either remained in their homes or sought shelter at locations such as the New Orleans Convention Center or the Louisiana Superdome. As the already strained levee system continued to give way, the remaining residents of New Orleans were faced with a city that by August 30 was 80 percent underwater. Many local agencies found themselves unable to respond to the increasingly desperate situation, as their own headquarters and control centres were under 20 feet (6 metres) of water. With no relief in sight and in the absence of any organized effort to restore order, some neighbourhoods experienced substantial amounts of looting, and helicopters were used to rescue many people from rooftops in the flooded Ninth Ward.

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Hurricane Katrina | Deaths, Damage, & Facts

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Hurricane Katrina, tropical cyclone that struck the southeastern United States in August 2005, breaching levees and causing widespread death and damage. Ultimately, the storm caused more than $160 billion in damage, and it reduced the population of New Orleans by 29 percent between the fall of 2005 and 2011.

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Encyclopedic Entry Vocabulary

Geologists, scientists who study the physical formations of the Earth, sometimes describe landslides as one type of mass wasting. A mass wasting is any downward movement in which the Earth's surface is worn away. Other types of mass wasting include rockfalls and the flow of shore deposits called alluvium.

Near populated areas, landslides present major hazards to people and property. Landslides cause an estimated 25 to 50 deaths and $3.5 billion in damage each year in the United States.

Geology refers to characteristics of the material itself. The earth or rock might be weak or fracture d, or different layers may have different strengths and stiffness.

Morphology refers to the structure of the land. For example, slopes that lose their vegetation to fire or drought are more vulnerable to landslides. Vegetation holds soil in place, and without the root system s of trees, bushes, and other plants, the land is more likely to slide away.

A classic morphological cause of landslides is erosion, or weakening of earth due to water. In April 1983, the town of Thistle, Utah, experienced a devastating landslide brought on by heavy rains and rapidly melting snow. A mass of earth eventually totaling 305 meters wide, 61 meters thick, and 1.6 kilometers long (1,000 feet wide, 200 feet thick, and one mile long) slid across the nearby Spanish Fork River, damming it and severing railroad and highway lines. The landslide was the costliest in U.S. history, causing over $400 million in damage and destroying Thistle, which remains an evacuated ghost town today.

There are many ways to describe a landslide. The nature of a landslide's movement and the type of material involved are two of the most common.

There are several ways of describing how a landslide moves. These include falls, topples, translational slides, lateral spreads, and flows.

In falls and topples, heavy blocks of material fall after separating from a very steep slope or cliff. Boulders tumbling down a slope would be a fall or topple.

In translational slides, surface material is separated from the more stable underlying layer of a slope. An earthquake may shake the loosen top layer of soil from the harder earth beneath in this type of landslide.

A lateral spread or flow is the movement of material sideways, or laterally. This happens when a powerful force, such as an earthquake, makes the ground move quickly, like a liquid.

A landslide can involve rock, soil, vegetation, water, or some combination of all these. A landslide caused by a volcano can also contain hot volcanic ash and lava from the eruption. A landslide high in the mountains may have snow and snowmelt.

Volcanic landslides, also called lahars, are among the most devastating type of landslides. The largest landslide in recorded history took place after the 1980 eruption of Mount St. Helens in the U.S. state of Washington. The resulting flow of ash, rock, soil, vegetation and water, with a volume of about 2.9 cubic kilometers (0.7 cubic miles), covered an area of 62 square kilometers (24 square miles).

Another factor that might be important for describing landslides is the speed of the movement. Some landslides move at many meters per second, while others creep along at an centimeter or two a year. The amount of water, ice, or air in the earth should also be considered. Some landslides include toxic gases from deep in the Earth expelled by volcanoes. Some landslides, called mudslide s, contain a high amount of water and move very quickly. Complex landslides consist of a combination of different material or movement types.

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The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Writers

Kim Rutledge
Tara Ramroop
Diane Boudreau
Melissa McDaniel
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Mary Crooks, National Geographic Society
Tim Gunther

Editors

Jeannie Evers, Emdash Editing
Kara West

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

Last Updated

March 24, 2014

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This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Powered by Encyclopedic Entry Vocabulary Geologists, scientists who study the physical formations of the Earth, sometimes describe landslides as one type of mass wasting.

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How volcanoes formed the Hawaiian Islands

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At 2,624 years, a bald cypress is oldest known living tree in eastern North America

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Part 2: Changes to the Earth that affected a SMALL area 

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Part 2: Changes to the Earth that affected a SMALL area 

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Part 1: Changes to the Earth that affected a LARGE area 

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Part 1: Changes to the Earth that affected a LARGE area 

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Rare Video: Japan Tsunami | National Geographic

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Part 4: Changes to the Earth that happened QUICKLY (Over a short period of time)

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Part 4: Changes to the Earth that happened QUICKLY (Over a short period of time)

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Footage of the 1980 Mount St. Helens Eruption

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NASA Releases Time-Lapse Of the Disappearing Arctic Polar Ice Cap

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Watch An Oxbow Lake Form: Ucayali River: 1985 - 2013

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Arches National Park, one of Utah's most popular parklands, is made up of a fascinating collection of rock art, acres upon acres of slickrock and the world's largest concentration of natural arches. Created by various forms of weathering and erosion, these natural arches draw visitors from around the globe. But it's not just arches that create the park's intrigue, as seen here in this gravity defying roadside feature.
Balanced Rock, a natural wonder perched on a slanted pedestal, takes up as much space as three school buses. Standing about 128 feet high, Balanced Rock is one of many of the park attractions, but its easy access boosts it popularity. A short, level loop trail circles the rock and allows visitors to view this spectacle from any angle. Similar to most rock formations seen in Arches National Park, Balanced Rock and its sandstone pedestal is colored by a rich red iron oxide. Sandstone has varying degrees of hardness and is eroded away at different rates. A smaller balanced rock, called Chip off the Old Block, once stood beside the Balanced Rock but fell during the winter of 1975-76.
One powerful force of erosion is frost wedging. This phenomenon begins when moisture collects in small cracks of rock joints and crevices. Most materials shrink when chilled, but water has an unusual property, it expands when frozen. The moisture frozen between the rock creates a tremendous wedging force, causing the rock to separate further. Mid latitude daily freeze and thaw cycles slowly chip away at the rock layers, creating much of the rock art here in the park.

Area Map
Park Map

Copyright © 2019 Benjamin Prepelka
All Rights Reserved

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arches national park - utah; natural arches; colorado plateau province; four corners; la sal mountains; moab; courthouse towers; park avenue; sandstone fins; park avenue trail;

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Arches National Park, one of Utah's most popular parklands, is made up of a fascinating collection of rock art, acres upon acres of slickrock and the world's largest concentration of natural arches. Created by various forms of weathering and erosion, these natural arches draw visitors from around the globe.

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How the Earth Was Made: Hawaii | History

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Part 3: Changes to the Earth that happened slowly (Over a long period of time)

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Part 3: Changes to the Earth that happened slowly (Over a long period of time)

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Route 168 Landslide in Japan 国道168号線 地すべり