A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilizes as a slurry that flows downslope. Debris flows include <50% fines.
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:
- U.S. Landslide Inventory Map
- Inventory of Landslides Triggered by the 1994 Northridge, California, Earthquake
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 might form at a particular place, but also the chance that it might travel downslope a given distance.
Example 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).
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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 potential hazards posed by landslides produced from...
Under what circumstances do U.S. Geological Survey landslide personnel conduct field work in landslide-prone areas?
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Can major landslides and debris flows happen in all areas of the U.S.?
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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 subdivided by the type of geologic material...
A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilizes as a slurry that flows downslope. Debris flows include <50% fines.
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.
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.
![PubTalk 10/2016 — Rockfalls in California's Sierra Nevada](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/masonry/public/thumbnails/video/youtube-6xoXlgPksv4.jpg?itok=WEI1Uzlz)
Rock falls in California’s Sierra Nevada - Pursuing explanations for exfoliation and seemingly spontaneous fracture of rock
Rock falls in California’s Sierra Nevada - Pursuing explanations for exfoliation and seemingly spontaneous fracture of rock
![Landsat image showing the landslide in Glacier Bay](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/masonry/public/thumbnails/image/IOW_CLU_Glacier_Bay.jpg?itok=JNFuOsUt)
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.
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.
A volcano monitoring “spider” was deployed by helicopter to the Oso landslide to track ground movement and seismicity while search-and-rescue operations were ongoing. The spider was equipped with a seismometer (mounted on the far left leg) to track ground shaking and GPS (a dome-shaped instrument on the upper mast) to track subtle ground movement.
A volcano monitoring “spider” was deployed by helicopter to the Oso landslide to track ground movement and seismicity while search-and-rescue operations were ongoing. The spider was equipped with a seismometer (mounted on the far left leg) to track ground shaking and GPS (a dome-shaped instrument on the upper mast) to track subtle ground movement.
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.
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.
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.
Forecasting inundation of catastrophic landslides from precursory creep
National strategy for landslide loss reduction
Science for a risky world—A U.S. Geological Survey plan for risk research and applications
THRESH—Software for tracking rainfall thresholds for landslide and debris-flow occurrence, user manual
An open repository of earthquake-triggered ground-failure inventories
The 3D Elevation Program—Landslide recognition, hazard assessment, and mitigation support
Real-time monitoring of landslides
The Landslide Handbook - A Guide to Understanding Landslides
Video documentation of experiments at the USGS debris-flow flume 1992–2017
Southern California landslides-an overview
Landslide hazards: A national threat
Landslide overview map of the conterminous United States
Related Content
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 potential hazards posed by landslides produced from...
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 in foreign countries that request assistance...
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, Pennsylvania, Tennessee, North Carolina, Puerto...
What was the largest landslide in the United States? In the world?
The largest subaerial (on land) landslide in Earth's recorded history was connected with the 1980 eruption of Mount St. Helens volcano in Washington state, USA. That landslide had a volume of 2.8 cubic kilometers (0.67 cubic miles) of material and the landslide traveled about 22.5 kilometers (14 miles) down the North Fork Toutle River. Average landside depth was 46 meters (150 feet) with a maximum...
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). Twenty-three people were killed, at least 167 injured, and more than 400 homes were damaged by a series of debris flows that impacted the...
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 subdivided by the type of geologic material...
A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilizes as a slurry that flows downslope. Debris flows include <50% fines.
A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilizes as a slurry that flows downslope. Debris flows include <50% fines.
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.
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.
![PubTalk 10/2016 — Rockfalls in California's Sierra Nevada](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/masonry/public/thumbnails/video/youtube-6xoXlgPksv4.jpg?itok=WEI1Uzlz)
Rock falls in California’s Sierra Nevada - Pursuing explanations for exfoliation and seemingly spontaneous fracture of rock
Rock falls in California’s Sierra Nevada - Pursuing explanations for exfoliation and seemingly spontaneous fracture of rock
![Landsat image showing the landslide in Glacier Bay](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/masonry/public/thumbnails/image/IOW_CLU_Glacier_Bay.jpg?itok=JNFuOsUt)
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.
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.
A volcano monitoring “spider” was deployed by helicopter to the Oso landslide to track ground movement and seismicity while search-and-rescue operations were ongoing. The spider was equipped with a seismometer (mounted on the far left leg) to track ground shaking and GPS (a dome-shaped instrument on the upper mast) to track subtle ground movement.
A volcano monitoring “spider” was deployed by helicopter to the Oso landslide to track ground movement and seismicity while search-and-rescue operations were ongoing. The spider was equipped with a seismometer (mounted on the far left leg) to track ground shaking and GPS (a dome-shaped instrument on the upper mast) to track subtle ground movement.
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.
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.
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.