Landslide & Debris Flow (Mudslide) Preparedness Guide

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,
• alternate freezing or thawing,
• and steepening of slopes by erosion or human modification.

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 can flow 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. 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.

Recognize Landslide Warning Signs

• Changes occur in your landscape such as patterns of storm-water drainage on slopes (especially the places where runoff water converges) land movement, small slides, flows, or progressively leaning trees.
• Doors or windows stick or jam for the first time.
• 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.
• Water breaks through the ground surface in new locations.
• Fences, retaining walls, utility poles, or trees tilt or move.
• A faint rumbling sound that increases in volume is noticeable as the landslide nears.
• The ground slopes downward in one direction and may begin shifting in that direction under your feet.
• Unusual sounds, such as trees cracking or boulders knocking together, might indicate moving debris.
• Collapsed pavement, mud, fallen rocks, and other indications of possible debris flow can be seen when driving (embankments along roadsides are particularly susceptible to landslides).

Before a Landslide or Debris Flow

During a Landslide or Debris Flow

After a Landslide or Debris Flow

All information above is from the FEMA or Ready.gov website.

For more information and resources on Landslide Preparedness, please visit the web sites below.

US Department of Homeland Security – FEMA
http://www.fema.gov/

American Red Cross
http://www.redcross.org/

Ready Gov
http://www.ready.gov/

CDC – Center For Disease Control and Prevention
http://www.cdc.gov/