Landslides and Mudflows Banner

What are Landslides?

A landslide is a mass of rock, earth, or debris moving down a slope. They are activated by rainstorms, earthquakes, volcanic eruptions, fires, and by human modification of the land.

Landslides Facts and Mudflow Facts

Landslide Facts

  • Landslides may be very small or very large and can move from slow to very high speeds.
  • It is estimated that landslides cause between 25 and 50 deaths each year in the U.S. and thousands more in vulnerable areas all around the globe.

Mudflow Facts

  • Mudflows may be very small or very large; flowing rapidly down slopes or through channels, and can strike with little or no warning.
  • A mudflow can travel several miles from its source, growing in size as it picks up trees, vehicles, and other materials along the way.

Danger Zones

  • Landslides may occur in all U.S. states/territories; California, West Virginia, Utah, Kentucky, Tennessee, Puerto Rico, Ohio, and Washington are at greatest risk.

Landslide Warning Signs

  • Doors or windows begin to stick or jam.
  • New cracks appear in plaster, tile, brick, or foundations.
  • Outside walls, walks, or stairs begin pulling away from the building.
  • Slowly developing, widening cracks appear on the ground or on paved areas such as streets or driveways.
  • Underground utility lines break.
  • Bulging ground appears at the base of a slope.
  • Fences, retaining walls, utility poles, or trees tilt or move.
  • The ground slopes downward in one specific direction and may begin shifting in that direction under your feet.
  • Be alert for sudden increases or decreases in water flow and a change from clear to muddy water if you are near a stream or channel.

Actions to Consider


  • Create an evacuation plan for your family and have a backup route in mind.
  • Be prepared to evacuate if instructed to do so.
  • Listen for unusual sounds such as trees cracking or boulders knocking.
  • Plant ground cover on slopes and build retaining walls.

If Indoors

  • Stay indoors. Move to a second story if possible.
  • Take cover under a desk, table, or other piece of sturdy furniture.

If Outdoors

  • Get out of the path of the landslide or mudflow. Run to the nearest high ground in a direction away from the path. Do not delay! Save yourself, not your belongings.
  • Run for the nearest shelter such as a group of trees or a building if rocks and other debris are approaching.
  • Curl into a tight ball and protect your head if escape is not possible.


  • Stay away from the slide area; there may be danger of additional slides.
  • Check for injured or trapped people near the slide area. Provide first aid and CPR if trained to do so.
  • Listen to local radio or television stations for the latest emergency information.
  • Help a neighbor who may require special assistance - large families, children, elderly, and individuals with disabilities.
  • Check the building foundation, chimney, and surrounding land for damage. Be especially careful to check for downed power lines and gas lines that may have ruptured.
  • Replant damaged ground as soon as possible since erosion caused by loss of ground cover can lead to flash flooding.
  • Report property damage to your insurance agent immediately.

Did You Know...

The May 1980 eruption of the Mount St. Helens volcano caused the largest landslide in history - a rock slide-debris avalanche large enough to fill 250 million dump trucks.

Contact your local or Installation's Office of Emergency Management for more information.