Faults and Earthquakes in San Diego County Like the rest of
southern California, San Diego County has a number of active
earthquake faults. These faults generally run in a northwest-
southeast direction and are the product of crustal stresses
associated with movement of the Pacific and North American
lithospheric plates. From east to west the major active faults
consist of the San Jacinto, Elsinore, La Nacion, and Rose Canyon
faults onshore and the Coronado Bank, San Diego Trough, and San
Clemente faults offshore. Often the traces of these faults are
marked by river valleys and canyons such as in the Lake Henshaw
area where the Elsinore Fault passes along the northeast shore
of the lake, or in Balboa Park where the small Florida Canyon
Fault passes along the western slope of the canyon and beneath
the parking lot of the Naval Hospital. Since 1984 earthquake
activity in San Diego County has doubled over that of the
preceding 50 years. In modern times the strongest recorded quake
(seismographs were not developed