The world's biggest fault line is the San Andreas Fault. The fault extends more than 800 miles northwestward from the Gulf of California through the state and into parts of the Pacific Ocean.
The fault serves as the boundary between the two major plates of the Earth's crust: the Pacific and North American plates. Tectonic movement along the fault has been associated with several earthquakes originating near its surface, including San Francisco quakes in 1906 and 1989 and a destructive quake in suburban Los Angeles in 1994. University of California-Berkeley professor of geology Andrew Larson is credited with discovering the fault in 1895.