A landslide occurs when rock, debris, or earth moves down a slope. Typically, landslides are triggered by forces like heavy rainfall, snowmelt, earthquakes, human activities, or some combination of factors. Often, they're impossible to predict.

Landslide causes road to break away
Landslides are triggered by forces like heavy rainfall, snowmelt, earthquakes, human activities, or some combination of factors. 

Landslides occur in all U.S. states and territories, and usually strike without warning. The force of rocks, soil, or other debris moving down a slope can devastate anything in its path. Landslides can be activated by:

  • Alternate freezing or thawing
  • Heavy rainfall
  • Earthquakes
  • Fires
  • Steepening of slopes by erosion or human modification
  • Storms

Landslide problems can be caused by land mismanagement, particularly in mountain, canyon, and coastal regions. In areas burned by forest and brush fires, a lower threshold of precipitation may initiate landslides. Land-use zoning, professional inspections, and proper design can minimize many landslide, mudflow and debris-flow problems.

What to do before, during and after a landslide