Slump

From Wikipedia, the free encyclopedia

For the anime and manga, see Dr. Slump.

The slump that destroyed Thistle, Utah, by creating an earthen dam that flooded the area

Slump is a form of mass wasting event that occurs when loosely consolidated materials or rock layers move a short distance down a slope. When the movement occurs in soil, there is often a distinctive rotational movement to the mass, that cuts vertically through bedding planes (landslides take place along a bedding plane or fault). This results in internal deformation of the moving mass consisting chiefly of overturned folds called "sheath folds." The surface of the mass often remains relatively undisturbed, especially at the top. The area where the mass broke away from the slope is often cliff-like and concave. This area is known as the "scarp."

The speed of slump varies widely, ranging from meters per second, to meters per year. Sudden slumps usually occur after earthquakes or heavy continuing rains. The rain provides lubrication for the material to slide, and increases the self-mass of the material. Both factors increase the rate of slumping.