Historic Earthquakes
San Fernando, California
1971 02 09 14:00 UTC
Magnitude 6.6
Intensity XI
This destructive earthquake occurred in a sparsely populated area of the San Gabriel Mountains, near San Fernando. It lasted about 60 seconds, and, in that brief span of time, took 65 lives, injured more than 2,000, and caused property damage estimated at $505 million.
The earthquake created a zone of discontinuous surface faulting, named the San Fernando fault zone, which partly follows the boundary between the San Gabriel Mountains and the San Fernando - Tujunga Valleys and partly transects the northern salient of the San Fernando Valley. This latter zone of tectonic ruptures was associated with some of the heaviest property damage sustained in the region. Within the entire length of the surface faulting, which extended roughly east-west for about 15 kilometers, the maximum vertical offset measured on a single scarp was about 1 meter, the maximum lateral offset about 1 meter, and the maximum shortening (thrust component) about 0.9 meters.
The most spectacular damage included the destruction of major structures at the Olive View and the Veterans Administration Hospitals and the collapse of freeway overpasses. The newly built, earthquake-resistant buildings at the Olive View Hospital in Sylmar were destroyed - four five-story wings pulled away from the main building and three stair towers toppled. Older, unreinforced masonry buildings collapsed at the Veterans Administration Hospital at San Fernando, killing 49 people. Many older buildings in the Alhambra, Beverly Hills, Burbank, and Glendale areas were damaged beyond repair, and thousands of chimneys were damaged in the region. Public utilities and facilities of all kinds were damaged, both above and below ground.
Severe ground fracturing and landslides were responsible for extensive damage in areas where faulting was not observed. The most damaging landslide occurred in the Upper Lake area of Van Norman Lakes, where highway overpasses, railroads, pipelines, and almost all structures in the path of the slide were damaged severely. Several overpasses collapsed. Two dams were damaged severely (Lower Van Norman Dam and Pacoima Dam), and three others sustained minor damage. Widespread landslides and rockfalls blocked many highways in the area.
Felt throughout southern California and into western Arizona and southern Nevada. No foreshocks were recorded, but aftershocks were reported in the area for several months.
Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.
See also: the San Fernando Earthquake.
