When Is Mud Dangerous?
ES1204  Rain-Induced Mudslides

Robert Schuster, USGS
La Conchita, California

Heavy rains are a common cause of mudslides. Water acts as a lubricant between soil particles, and the strength of saturated ground can be overcome by gravity. An entire hillside can begin flowing downhill if sufficiently soaked.

This landslide and debris flow occurred following rains in the spring of 1995. The houses nearest the slide were completely destroyed.

  !   Move your cursor over the image to highlight the area that slid down.

Hurricanes bring incredible amounts of rain to an area in a short period of time. Damage from flooding following a hurricane is often worsened when hillsides fail and mud flows into an area.

Click Lahars to view photographs of mudslides triggered by heavy rains from Hurricane Mitch in Nicaragua.

  !   After you view the images, close the extra browser window and return to this investigation.


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