Why study landslides?

Landslides are a serious geologic hazard common to almost every State in the United States. 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 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. It is also important to understand the science of landslides – their causes, movement characteristics, soil properties, the geology associated with them, and where they are likely to occur.

The USGS Landslide Hazards Program helps address these needs for improved understanding by conducting research on several fundamental aspects of landslides. Thus, USGS landslide research seeks answers to such questions as these:

  • Where and when will landslides occur?
  • How big will they be?
  • How fast and how far will landslides move?

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What should I know about wildfires and debris flows?

Wildland 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...

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 can also result from the eruption or collapse of island or coastal volcanoes and from giant landslides on marine margins. These landslides, in turn, are often triggered by earthquakes. Tsunamis can be generated on...

Under what circumstances do U.S. Geological Survey landslide personnel conduct field work in landslide-prone areas?

USGS landslide researchers have ongoing field projects in several areas of the United States, including parts of the Pacific coastal ranges, Rocky Mountains, and the Appalachians. USGS scientists also respond to major landslide events, including some that result in federally-declared disasters. In some cases, USGS scientists respond to landslides...

Can major landslides and debris flows happen in all areas of the U.S.?

Landslides can and do occur in every state and territory of the U.S.; however, the type, severity and frequency of landslide activity varies from place to place, depending on the terrain, geology, and climate. Major storms have caused major or widespread landslides in Washington state, Oregon, California, Colorado, Idaho, Hawaii, Virginia, Ohio,...

Is there a list of the largest landslides in the world?

See the list of Catastrophic Landslides of the 20th Century - Worldwide . The five largest Worldwide Landslides are: 1911 - Tadzhik Republic - 2,000,000,000 cubic meters of material - 54 killed 1919 - Indonesia - 185 square kilometers of material - 5,110 killed 1920 - China - unknown volume - 100,000 killed 1921 - Kazakh Republic - unknown volume...

What was the biggest landslide in the world?

The largest landslide on Earth in recorded history 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 0.67 cubic miles (2.8 cubic kilometers) and the landslide traveled about 14 miles down the North Fork Toutle River. Average landslide depth...

What is the difference between a landslide advisory, a landslide watch, and a landslide warning?

An advisory is 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. A watch means that landslide-...

How many deaths result from landslides each year?

An average of 25-50 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 falls, debris-flows, or volcanic debris flows (called lahars). At least 20 people were killed by a series of mudslides in California's Santa Barbara...

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, poorly planned alteration of drainage patterns, and disturbing old landslides. Detailed on-site...

What is a landslide and what causes one?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further...
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Date published: July 20, 2017

Landslide Assistance from the Air

The USGS uses cutting edge technologies to investigate and forecast landslides and other natural hazards.

Date published: July 11, 2017

Huge landslide on California’s Big Sur coast continues to change

The Mud Creek landslide on California’s Big Sur coast keeps eroding.

Date published: June 1, 2017

USGS maps, measures huge landslide on California's Big Sur coast

USGS scientists analyzing before-and-after air photos have calculated the size of the May 20 landslide on California’s Big Sur coast, about 140 miles south of San Francisco. 

Date published: September 16, 2016

EarthView–Landslide Spreads 6 Miles Across Glacier Bay National Park

Two snapshots from Landsat show the extent of a landslide in an Alaska National Park.

Date published: July 28, 2015

Landslides Triggered by Nepal Earthquakes

MENLO PARK, Calif. — A new report from the U.S. Geological Survey provides critical landslide-hazard expertise to Nepalese agencies and villages affected by the April 25, magnitude 7.8 earthquake that shook much of central Nepal.

Date published: June 25, 1999

Landslides Will Continue to Impact U.S. - Tumbling Rocks Cost Dollars and Lives

Scenic rock cliffs falling to valley floors, rocks ripping out mountainsides, mud and debris moving down valleys at deadly speeds, mines and caves collapsing, and ocean and river bluffs sliding into the water -- all describe one of the nation’s most underestimated hazards -- landslides.

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Big Sur landslide on May 20, 2017 showing material across Highway 1.
May 27, 2017

Big Sur landslide on May 20, 2017

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Image: 2005 Landslide in Conchita, CA
March 14, 2016

2005 Landslide in Conchita, CA

This landslide occurred at La Conchita, California in 2005. Ten people were killed.

Attribution: Natural Hazards
Oso landslide. Huge swath of mountain missing.
December 31, 2014

Oso landslide

Oso landslide 2014

Attribution: Natural Hazards
Image: 2014 Landslide in Washington State
March 24, 2014

2014 Landslide in Washington State

Photograph from an aerial survey showing the extent and impacts from the landslide in northwest Washington that occurred on March 22, 2014. The survey was conducted by the Washington State Department of Transportation, Washington State Department of Natural Resources, USGS, and King County Sheriff's Office.

Attribution: Natural Hazards
May 9, 2012

Volcano Web Shorts 2: Debris Flows

Debris flows are hazardous flows of rock, sediment and water that surge down mountain slopes and into adjacent valleys. Hydrologist Richard Iverson describes the nature of debris-flow research and explains how debris flow experiments are conducted at the USGS Debris Flow Flume, west of Eugene, Oregon. Spectacular debris flow footage, recorded by Franck Lavigne of the

...
Landslide monitoring station with the San Gabriel mountains in the background, post wildfire with no vegetation
December 31, 2009

Landslide monitoring site

Original rainfall and telemetry station established after the 2009 Station Fire, CA.

Image: Landslide Sampling
April 27, 2001

Landslide Sampling

Scientist Jonathan Godt samples a landslide headscarp in Alameda County, CA.

Attribution: Natural Hazards
Image: Coastal Landslide Caused by the 2010 Haiti Earthquake

Coastal Landslide Caused by the 2010 Haiti Earthquake

Earthquake-triggered landslide on south coast of Haiti near village of Nan Diamant.

Attribution: Natural Hazards
Image: 2008 Landslide Near Hongyan Resort, China

2008 Landslide Near Hongyan Resort, China

The May 12, 2008, Great Sichuan Earthquake, also called the Wenchuan Earthquake, occurred at 14:28 local time, in Sichuan Province, China. The earthquake magnitudes were Mw = 7.9 (USGS), Ms = 8.0 (Chinese Earthquake Administration). The epicenter was 80 km west-northwest of Chengdu, the capital city of Sichuan province. Damage by earthquake-induced landslides was

...
Attribution: Natural Hazards
Image: Landslides in Limestone, Haiti

Landslides in Limestone, Haiti

This photo shows a landslide that deposited disaggregated limestone fragments in river valley.

Attribution: Natural Hazards