List of earthquakes in California

The earliest known earthquake in the U.S. state of California was documented in 1769 by the Spanish explorers and Catholic missionaries of the Portolá expedition as they traveled northward from San Diego along the Santa Ana River near the present site of Los Angeles.

The outlook improved when Professor Andrew Lawson brought the state's first monitoring program online at the University of California, Berkeley in 1910 with seismologist Harry Wood, who was later instrumental in getting the Caltech Seismological Laboratory in Pasadena operational in the 1920s.

In both cases, the perception of California policy makers changed, and state laws and building codes were modified (with much debate) to require commercial and residential properties to be built to withstand earthquakes.

This system of faults terminates in the north at the Mendocino triple junction, one of the most seismically active regions in the state, where earthquakes are occasionally the result of intraplate deformation within the Gorda plate.

It terminates in the south at the Salton Sea where displacement transitions to a series of spreading centers and transform faults, beginning with the Brawley seismic zone in the Imperial Valley.

A paleoseismic investigation using Lidar revealed that more than 16 feet (5 m) of slip has accumulated since the 1857 event on the southern SAF, which borders the Mojave Desert to the north and east of the Greater Los Angeles Area.