1979 Imperial Valley earthquake occurred at 16:16 Pacific Daylight Time ( 23:16 UTC ) on 15 October just south of the Mexico – United States border . It affected Imperial Valley in Southern California and Mexicali Valley in northern Baja California . The earthquake had a relatively shallow hypocenter and caused property damage in the United States estimated at $ 30 million USD . The irrigation systems in the Imperial Valley were badly affected , but no deaths occurred . It was the largest earthquake to occur in the contiguous United States since the 1971 San Fernando earthquake eight years earlier
1971 San Fernando earthquake
1971 San Fernando earthquake
1979 Imperial Valley earthquake