What is a landslide hazard map?

Several kinds of maps are used to depict danger from landslides. These maps may be as simple as a map that uses the locations of old landslides to indicate potential instability, or as complex as a quantitative map incorporating probabilities based on variables such as rainfall, slope angle, soil type, and levels of earthquake shaking. The following types of maps are used to describe and depict landslide hazards:

Landslide inventory maps show landslide locations and may show the dimensions and geographical extent of each landslide. Because one clue to the location of future landsliding is the distribution of past movement, maps that show the location and size of landslides are helpful in predicting the hazard for an area.  

Examples of landslide inventory maps:

Landslide susceptibility maps describe the relative likelihood of future landsliding based solely on the intrinsic properties of a locale or site. Some organizations use the term “landslide potential map” for maps of this kind. Prior failure (from a landslide inventory), rock or soil strength, and steepness of slope are three of the more important site factors that determine susceptibility.

Examples of landslide susceptibility maps:

Landslide hazard maps indicate the possibility of landslides occurring throughout a given area. An ideal landslide hazard map shows not only the chances that a landslide may form at a particular place, but also the chance that it may travel downslope a given distance.

Examples of landslide hazard maps:

Examples of potential landslide maps:

Landslide risk maps show landslide potential along with the expected losses to life and property, should a landslide occur. Risk maps combine the probability information from a landslide hazard map with an analysis of all possible consequences (property damage, casualties, and loss of service).

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Oso landslide. Huge swath of mountain missing.
2014 (approx.)

Oso landslide 2014

Image: 2014 Landslide in Washington State
March 24, 2014

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.

June 10, 2012

Landslides occur in all 50 states and U.S. territories, and cause $1-2 billion in damages and more than 25 fatalities on average each year. USGS scientists aim to improve our understanding of landslide hazards to help protect communities and reduce associated losses.

 

 

 

Video Sections:

  • Types of Landslides
  • USGS Science
  • Did You See It?
  • Debris Flow Early Warning System (NOAA Partnership)
  • Tips for Homeowners
  • Conclusion
May 9, 2012

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 Universite Paris, makes clear the destructive power of these flows.

USGS
June 19, 2008

Listen to hear the answer.

Image: 2005 Landslide in La Conchita, CA
January 10, 2005

On January 10, 2005, a landslide struck the community of La Conchita in Ventura County, California, destroying or seriously damaging 36 houses and killing 10 people. For a USGS rerpot on this event, please see USGS Open-file report, "Landslide Hazards at La Conchita, California."