As it passes the towns of Gorman, Tejon Pass and Frazier Park, the fault begins to bend northward, forming the "Big Bend". The fault continues northwest alongside the Elizabeth Lake Road to the town of Elizabeth Lake. In Palmdale, a portion of the fault is easily examined at a roadcut for the Antelope Valley Freeway. These mountains are a result of movement along the San Andreas Fault and are commonly called the Transverse Range. The fault then runs along the southern base of the San Bernardino Mountains, crosses through the Cajon Pass and continues northwest along the northern base of the San Gabriel Mountains. Box Canyon, near the Salton Sea, contains upturned strata associated with that section of the fault. The southern segment (also known as the Mojave segment) begins near Bombay Beach, California. The Vasquez Rocks in Agua Dulce, California are evidence of the San Andreas Fault and part of the 2,650-mile Pacific Crest Trail. While the southern section of the fault and the parts through Parkfield experience earthquakes, the rest of the central section of the fault exhibits a phenomenon called aseismic creep, where the fault slips continuously without causing earthquakes. The central segment of the San Andreas Fault runs in a northwestern direction from Parkfield to Hollister. After that, it runs underwater along the coast until it nears Cape Mendocino, where it begins to bend to the west, terminating at the Mendocino Triple Junction. (In this region around the San Francisco Bay Area several significant "sister faults" run more-or-less parallel, and each of these can create significantly destructive earthquakes.) From Fort Ross, the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, runs just east of Bodega Head through Bodega Bay and back underwater, returning onshore at Fort Ross. The fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County. This is the approximate location of the epicenter of the 1906 San Francisco earthquake. The northern segment of the fault runs from Hollister, through the Santa Cruz Mountains, epicenter of the 1989 Loma Prieta earthquake, then up the San Francisco Peninsula, where it was first identified by Professor Lawson in 1895, then offshore at Daly City near Mussel Rock. Ī map displaying each of the seven major faults in the San Francisco Bay Area, and the probability of an M6.7 earthquake or higher occurring on each fault between 20. A project called the San Andreas Fault Observatory at Depth (SAFOD) near Parkfield, Monterey County, involved drilling through the fault during 2004–2007 to collect material and make physical and chemical observations to better understand fault behavior. In 1953, geologist Thomas Dibblee concluded that hundreds of miles of lateral movement could occur along the fault. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California. However, according to some of his reports from 18, Lawson actually named it after the surrounding San Andreas Valley. It is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. The fault was identified in 1895 by Professor Andrew Lawson of UC Berkeley, who discovered the northern zone. The slip rate along the fault ranges from 20 to 35 mm (0.79 to 1.38 in)/yr. The fault divides into three segments, each with different characteristics and a different degree of earthquake risk. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers (750 mi) through California. Plaque showing location of San Andreas Fault in San Mateo County