San Andreas Fault

San Andreas Fault, break in the earth's crust running 600 mi (965 km)from Cape Mendocino, northwestern Calif., to the Colorado desert. It was the sudden movement of land along this fault that caused the San Francisco Earthquake of 1906. The fracture, and the motion responsibile for this and other quakes, is a result of the abutment of the eastern Pacific and North American plates.

See also: Earthquake.