It is recognized as the world's best-known earthquake fault. The 800-mile long San Andreas fault, a continuous break in the Earth's crust that extends from Humboldt County in Northern California to the remote Salton Sea in southeastern California's Imperial County, marks the spot where two tectonic plates meet in the nation's most populous state.
The Pacific plate to its west and the North American plate to the east of the fault have been moving slowly for millions of years in what's known as strike-slip displacement. Smaller faults branch out from the 10-mile-deep San Andreas, creating a network of faults that extend into other parts of California.
Thousands of small earthquakes occur in California every year, but the largest known quakes on the San Andreas fault were in 1857 and 1906. The January 1857 Fort Tejon quake in Southern California and the April 1906 San Francisco quake were both estimated at magnitude-7.9. The San Francisco earthquake resulted in devastating fires. About 700 people were killed.
The photos below show what you'll find along the southern portion of the San Andreas Fault east of Los Angeles.