What is a landslide?

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Definition

A landslide is a type of "mass wasting." Mass wasting is down slope movement of soil and/or rock under the influence of gravity. A landslide is a movement of mass rock, debris, or earth down a slope. The failure of the slope happens when gravity exceeds the strength of the earth materials. Click here to learn about the different types of landslides right away, or stick around to learn about the different parts of a landslide (USGS).

(Feb, 1976, landslide caused by Guatemalan earthquake, photo by E.L. Harp, U.S.G.S.)

Anatomy of a Landslide

	Scarp - a scar of exposed soil on the landslide
	Crown - stable top soil at the head of the landslide. Sometimes the crown will fall and form a new scarp.
	Slip Plane - failure surface of a landslide
	Toe - material pushed out at the base of the landslide beyond the slip plane, supports the landslide.
	Rubble - debris from the landslide
	Bedrock - solid rock beneath the soil. The most common bedrock for a landslide to occur on is shale.
	Head - used to be part of the original ground surface
	Soil - loose upper layer of earth, clay soil often leads to landslides.

So now you know what landslides are, but what causes them? Read on to find out.

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