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Landslides and Debris Flow (Mudslide)

Landslides occur in all U.S. states and territories. In a landslide, masses of rock, earth, or debris move down a slope. Landslides may be small or large, slow or rapid. They are activated by storms, earthquakes, volcanic eruptions, fires, and human modification of land.

Debris and mud flows are rivers of rock, earth, and other debris saturated with water. They develop when water rapidly accumulates in the ground, during heavy rainfall or rapid snowmelt, changing the earth into a flowing river of mud or “slurry.” They flow can rapidly, striking with little or no warning at avalanche speeds. They also can travel several miles from their source, growing in size as they pick up trees, boulders, cars, and other materials.

Landslide problems can be caused by land mismanagement, particularly in mountain, canyon, and coastal regions. Land-use zoning, professional inspections, and proper design can minimize many landslide, mudflow, and debris flow problems.

Landslide overview map of the continental united states

Take Protective Measures

Before a Landslide orDebris Flow

The following are steps you can take to protect yourself from the effects of a landslide or debris flow:

Recognize Landslide Warning Signs

During a Landslide or Debris Flow

The following are guidelines for what you should do if a landslide or debris flow occurs:

After a Landslide or Debris Flow

The following are guidelines for the period following a landslide:

Image of landslide

Knowledge Check

Review the following information and answer the questions. Check your responses with the answer key.

Landslides occur in all 50 states - it is estimated that they cause between 25 and 50 deaths each year in the U.S. and thousands more in vulnerable areas around the globe. The number of landslides in the United States is expected to increase.

  1. What might account for the projected increase in landslides?
  2. What can you do to help reverse the upward trend?

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Last Modified: Friday, 30-May-2008 10:31:07 EDT