Landslides

Photo Credit: USGS -Geologic Hazards Team is located in Golden, Colorado
Landslides and Debris Flows (Mudslides)

Landslides occur in all U.S. states and territories. In a landslide, masses of rock, earth, or debris move down a slope. They may be small or large, slow or rapid. Landslides are caused by disturbances in the natural stability of a slope and can be activated by storms, earthquakes, volcanic eruptions, fires, and human modification of land.
 
Debris flows, also known as mudslides, develop when water rapidly accumulates in the ground and results in a surge of water-saturated rock, earth, and debris. Mudslides usually start on steep slopes and can be activated by natural disasters. Areas where wildfires or human modification of the land have destroyed vegetation on slopes are particularly vulnerable to landslides during and after heavy rains. They can flow rapidly, striking with little or no warning at avalanche speeds. They can also travel several miles from their source, growing in size as they pick up trees, boulders, cars, and other materials.

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