The location and when it was formed.
San Andreas Fault Carrizo Plain National Monument, California.The largest historical earthquakes that occurred along the San Andreas fault were those in 1857 and 1906. The earthquake of January 9, 1857, in southern California apparently was about the same magnitude as the San Francisco earthquake of 1906.
Plate Boundaries
Two of these moving plates meet in western California; the boundary between them is the San Andreas fault. The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault.
