The San Andreas Fault in California is creeping slowly but may soon give the country a jolt, similar to the 1906 earthquake that killed 3,000 and leveled San Francisco.
The 800-mile-long fault runs from north to south through California and Mexico, forming the boundary between the North American and Pacific tectonic plates. The two plates grind against each other along the fault, producing seismic events, moving 0.79 to 1.38 inches per year in a process called continental drift.
