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:
- 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 Potential Landslide Areas
- 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).
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...Read Full Answer
Tsunamis are large, potentially deadly and destructive sea waves, most of which are formed as a result of submarine earthquakes. They may also result from the eruption or collapse of island or coastal volcanoes and the formation of giant landslides on marine margins. These landslides, in turn, are often triggered by...Read Full Answer
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 U.S., 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, and in some cases, foreign countries...Read Full Answer
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,...Read Full Answer
See the list of worldwide catastrophic landslides of the 20th century.
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
The world's biggest historic landslide 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 2.8 cubic kilometers (km).
The world's biggest prehistoric landslide, discovered so far on land, is in southwestern Iran,...Read Full Answer
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...Read Full Answer
The U.S. Geological Survey derives its leadership role in landslide hazard-related work from the Disaster Relief Act of 1974 (the Stafford Act). The Director of the USGS has been delegated the responsibility to issue warnings for an earthquake, volcanic eruption, landslide, or other geologic catastrophe (1974 Disaster...Read Full Answer
An average of between 25 and 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 fall, debris-flows, or volcanic debris flows (called lahars). Debris flows occurring in December, 2003, killed 16...Read Full Answer
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, of poorly planned alteration of drainage patterns, and of disturbing old landslides...Read Full Answer
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...Read Full Answer
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...Read Full Answer
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.
New mapping in the western portion of the Columbia Gorge in Skamania County, Washington, shows previously unrecognized landslides beneath dense forest cover.
Two snapshots from Landsat show the extent of a landslide in an Alaska National Park.
New report identifies best practices for protecting communities
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.
Excerpt from the USGS Scientific Investigations Map 3358, “Landslides in the Western Columbia Gorge, Skamania County, Washington."
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.
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.
- Types of Landslides
- USGS Science
- Did You See It?
- Debris Flow Early Warning System (NOAA Partnership)
- Tips for Homeowners
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.
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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."