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What You Need to Know About a Mudslide

A mudslide, also known as debris flow or, is fast-moving fluid-like landslide which flows downhill in channels. Landslides are caused by disturbances in the natural stability of a slope. They are often brought on by heavy rains or follow droughts, earthquakes, or volcanic eruptions.

According to the Centers for Disease Control (CDC) landslides and debris flows result in 25 to 50 deaths each year in the United States.

Mudslides develop when water rapidly accumulates in ground soil and mud, resulting in a surge of rock, earth, and other organic debris. They usually start on steep slopes, and may be activated by natural disasters, such as rains resulting from a hurricane.

In the United States, mudslides result in tens of deaths every year. Educate yourself on the dangers of mudslides, and develop a plan of action in the event of an occurrence. This will be important to your survival during or after a natural disaster that triggers such an event.

Hazards associated with mudslides:

  • Fast-flowing water and debris that can lead to injury
  • Broken electrical, water, gas, and sewage lines
  • Ruined railroads and highways

Areas at risk:

  • Areas where human activity has destroyed vegetation on hills and mountainsides or where wildfires have occurred
  • Areas where mudslides previously occurred
  • Steep slopes
  • Bottoms of slopes or canyons
  • Physically altered slopes for construction of buildings and roads
  • River and stream channels
  • Places where surface runoff is directed to flow

Educate yourself before significant rainfall:

  • Remember that steep slopes and areas that have been burned off are prone to mudslide activity.
  • Contact local authorities, such as a county geologist, state geological surveys or departments of natural resources and see if mudslides have happened in your area.
  • Plan out evacuation plans for your family or business.

After a Landslide or Mudslide

  • Stay away from the specific disaster site.  Additional activity may take place.
  • Check for injured or trapped people near the slide area without entering the actual path of destruction.
  • Pay close attention to radio or TV information in regards to the disaster.
  • Report any broken utility lines to the correct authorities in your community.
  • Consult with a professional engineer with soils engineering expertise for advice on reducing additional landslide problems and risks. Local authorities should be able to tell you how to contact a geotechnical expert.


Federal Emergency Management Agency

U.S. Geological Survey (USGS)

American Red Cross (ARC)

United States Geological Survey (USGS)

Center for Disease Control