The history of earthquake investigations in California has been largely focused on the San Andreas Fault System , due to its strong influence in the state as the boundary between the Pacific Plate and the North American Plate ; it is the most studied fault on Earth . Andrew Lawson , a geologist from the University of California , Berkeley , had named the fault after the San Andreas Lake ( prior to the occurrence of the 1906 San Francisco earthquake ) and later led an investigation into that event . The San Andreas Fault ruptured for a length of during the 1906 shock , both to the north of San Francisco and to the south in the Santa Cruz Mountains region . Several long term forecasts for a large shock along the San Andreas Fault in that area had been made public prior to 1989 ( the event and its aftershocks occurred within a recognized seismic gap ) but the earthquake that transpired was not what had been anticipated . The 1989 Loma Prieta event originated on an undiscovered oblique-slip reverse fault that is located adjacent to the San Andreas Fault
1906 San Francisco earthquake
1906 San Francisco earthquake
1989 Loma Prieta earthquake