The San Andreas Fault is a major geological fault in California, extending about 1,200 kilometers (750 miles) from the northern end of the Gulf of California through western California to the Pacific Ocean near San Francisco. It marks the transform boundary between the Pacific Plate and the North American Plate, where they slide past each other laterally. This right-lateral strike-slip fault moves at an average rate of 20 to 35 mm per year, causing significant earthquakes, including the devastating 1906 San Francisco earthquake. The fault is divided into three segments (northern, central, and southern), each with distinct characteristics and earthquake risks. It passes through or near populated areas like Los Angeles and San Francisco and poses a major seismic hazard for these regions.
