U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005-3156

December 2005 Printed on recycled paper

A Nationwide Danger

Landslides occur and can cause damage in all 50 States. Severe storms, earthquakes, volcanic activity, coastal wave 

attack, and wildfires can cause widespread 

slope instability. Landslide danger may 

be high even as emergency personnel are 

providing rescue and recovery services. 

To address landslide hazards, several 

questions must be considered: Where and 

when will landslides occur? How big will 

the landslides be? How fast and how far 

will they move? What areas will the landslides affect or damage? How frequently 

do landslides occur in a given area? 

Answers to these questions are needed 

to make accurate landslide hazard maps 

and forecasts of landslide occurrence, and 

to provide information on how to avoid or 

mitigate landslide impacts.

The U.S. Geological Survey (USGS) 

develops methods to answer these questions to help protect U.S. communities 

from the dangers of landslides.

Landslide potential of the conterminous United States: Red areas have very high potential, 

yellow areas have high potential, and green areas have moderate potential. Landslides can 

and do occur in the black areas, but the potential is low. Map not to scale. Sources: the 

National Atlas and the USGS

Debris flows, triggered by a rainstorm, move 

into and above the Arapahoe Basin ski area 

in central Colorado in 1999. The rain led to 

debris flows along the Interstate 70 corridor 

in Colorado, from Georgetown to the Eisenhower Tunnel. (USGS photo/Ed Harp)

Landslide Hazards—A National Threat

Landslide potential of the conterminous United States 

Landslide Impacts USGS Science Priorities

• Cause damage in all 50 States, 

Puerto Rico, and the U.S. Virgin 

Islands

• Cost $3.5 billion per year, in 2005 

dollars, in damage repair

• Cause between 25 and 50 deaths in 

the United States annually

• Reduce real estate values and tourist revenue

• Lead to lost human, industrial, 

agricultural, and forest productivity

• Cause damage to the natural environment

• Develop predictive models to examine 

the potential for large, slow-moving 

landslides

• Advance existing models for the 

occurrence of fast-moving debris 

flows

• Develop tools to predict the characteristics of debris flows generated from 

recently burned areas

• Advance the operation of the joint 

National Oceanic and Atmospheric 

Administration-USGS Prototype 

Debris Flow Warning System

USGS Science Helps Build Safer Communities
Landslide Facts

• Landslides often accompany earthquakes, floods, storm surges, hurricanes, 

wildfires, or volcanic activity. They are often more damaging and deadly than the 

triggering event (examples: the 1964 Alaska earthquake-induced landslides and 

the 1980 Mount St. Helens volcanic debris flow).

• Human activities and population expansion are major factors in increased landslide damage and costs.

• The May 1980 eruption of Mount St. Helens caused the largest landslide in history—a rock slide-debris avalanche large enough to fill 250 million dump trucks 

to the brim traveled about 14 miles, destroying nine highway bridges, numerous 

private and public buildings, and many miles of highways, roads, and railroads. 

The debris avalanche also formed several new lakes by damming the North Fork 

Toutle River and its tributaries. These lakes posed hazards to downstream communities because of the possible failure of the dams, which could have resulted in 

catastrophic flooding.

• Although the National Flood Insurance Act covers certain damage from “mudflows,” insurance against landslides is generally unavailable in most areas of the 

United States. As a result, many victims of landslides resort to litigation in order 

to recover damages.

For More Information

USGS National Landslide Information 

Center: 1-800-654-4966

http://landslides.usgs.gov/

http://www.usgs.gov/

USGS Science Provides Solutions

The USGS Landslide Hazards Program strives to reduce loss of life and 

property from landslide hazards through 

improved understanding and effective 

mitigation. These goals are accomplished 

in three primary ways: (1) development 

of improved approaches for landslide 

hazard assessments; (2) post-disaster 

response; and (3) public information and 

outreach. 

In response to requests by Federal or 

State governments, the USGS assesses 

landslide hazards and offers technical 

assistance and information for recovery 

efforts.

Public education and outreach on landslide hazard issues are performed through 

the USGS National Landslide Information 

Center, which maintains an informational 

Web site at http://landslides.usgs.gov/, 

generates fact sheets and other educational literature, and responds to inquiries 

from the public. 

A Collaborative Strategy

USGS landslide researchers have partnered with local emergency-management, 

land-use planning and decisionmaking 

agencies, Federal and State land management agencies, State geological surveys, 

and universities. 

These partnerships have been used to 

promote the use of hazard assessment 

approaches developed by the USGS; map 

and inventory landslides; perform hazards 

assessments; and monitor landslides in 

critical areas for urban growth, lifelines, 

and transportation. 

For example, the National Oceanic 

and Atmospheric Administration and the 

USGS are conducting a pilot project in 

southern California to predict when flash 

floods and debris flows might occur in 

areas recently burned by wildfire. 

A National Outlook

The USGS has developed a comprehensive national strategy for addressing 

the widespread landslide hazards facing 

the Nation. 

This strategy, available at http://pubs.

usgs.gov/circ/c1244/, identifies nine 

major elements of a potential expanded 

national program for landslide mitigation: research; hazard mapping and 

assessments; real-time monitoring; loss 

assessment; information collection, interpretation, dissemination, and archiving; 

guidelines and training; public awareness and education; implementation of 

loss-reduction measures; and emergency 

preparedness, recovery, and response.

The USGS helps the public, policymakers, and the emergency management 

community make informed decisions on 

how to prepare for and react to landslide 

hazards and reduce losses from future 

landslides.

A rockslide on Highway 20 in Washington 

State cuts off access to Diablo, Wash., 

Sunday, November 9, 2003. The rockslide 

destroyed parts of the roadway and guardrail, 

and boulders and debris in excess of 100 

tons, including a 50-ton boulder, blocked both 

highway lanes. (Washington State Department 

of Transportation photo)

Homes lie damaged under this large earth 

flow in LaConchita, Calif., Saturday, March 

4, 1995. On January 10, 2005, a portion of this 

area became a debris flow during heavy 

rain, destroying several homes and killing 10 

people. (USGS photo/Robert L. Schuster)

This house was crushed by the LaConchita, 

Calif., earth flow, Saturday, March 4, 1995.

(USGS photo/Robert L. Schuster)