What is a landslide hazard map?
Several kinds of maps are used to depict danger from landslides. These maps might be as simple as a map that uses the locations of old landslides to indicate potential instability, or as complex as a 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 might show the dimensions and geographical extent of each landslide. One clue to the location of future landsliding is the distribution of past movement, so maps that show the location and size of landslides are helpful in predicting the hazard for an area.
Examples of landslide inventory maps:
- Inventory of Landslides Triggered by the 1994 Northridge, California, Earthquake
- California Geological Survey 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:
- Susceptibility to Deep-Seated Landslides in California
- Landslide Susceptibility Estimated From Mapping Using Light Detection and Ranging (LIDAR) Imagery and Historical Landslide Records, Seattle, Washington
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:
- NASA Global View of Landslide Susceptibility
- Assessing landslide potential using GIS, soil wetness modeling and topographic attributes, Payette River, Idaho - 2001
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).
Under what circumstances do U.S. Geological Survey landslide personnel conduct field work in landslide-prone areas?
Days after fatal debris flows devastated Southern California’s Montecito community, a team of U.S. Geological Survey geologists joined county, state, and federal partners to survey and evaluate the aftermath.
The Mud Creek landslide on California’s Big Sur coast keeps eroding.
USGS is collecting and analyzing air photos to help monitor a huge landslide that occurred May 20 on California’s Big Sur coast.
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.
USGS scientists continue to monitor the slide by collecting imagery every couple of weeks, weather permitting. Pilot Bob Van Wagenen, contracted through the Department of the Interior’s Office of Aviation Services, takes air photos for Jon Warrick’s Big Sur Landslide team, flying out of the Watsonville Municipal Airport in a Cessna 182R. He uses a camera-plus-GPS system...
Rock falls in California’s Sierra Nevada - Pursuing explanations for exfoliation and seemingly spontaneous fracture of rock
On June 28, 2016, a 4,000-foot-high mountainside in Glacier Bay National Park and Preserve collapsed, sending rocky debris equivalent to 60 million mid-size SUVs tumbling onto nearby Lamplugh Glacier. Almost 6 weeks later, on August 7, the Operational Land Imager sensor aboard Landsat 8 captured the black stain of the landslide in the image on the right. No such...
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.
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...
Downstream impacts of a post-fire debris-flow in Mullally Canyon on February 6, 2010, near La Canada-Flintridge, California. Debris flow was generated during a burst of high-intensity rainfall over the area burned by the September 2009 Station Fire.