Whittier Narrows earthquake
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The Whittier Narrows earthquake struck the southern San Gabriel Valley and surrounding communities of southern California at 7:42 a.m. (Pacific Daylight Time) on October 1, 1987. The magnitude 5.9 earthquake was originally assigned a magnitude of 6.0 but was revised a few days later when additional data became available. Its epicenter actually in the town of Rosemead, California at a depth of 11 km.
The earthquake was caused by slip on a blind thrust fault near the northern end of the Whittier Fault, part of the Elsinore Fault Zone, on a previously unknown fault structure. There was no surface rupture. It has been proposed that the event occurred on an extension of the recently recognized Puente Hills thrust system.
A magnitude 5.3 strike-slip aftershock occurred three days later, on October 4, causing additional damage.
Three people died as a direct result of the earthquake. One death was of a Southern California Edison worker buried by a landslide in the Muir Peak area of the San Gabriel Mountains while working with a crew installing high tension power lines north of Pasadena, California. Five other deaths are attributed indirectly to the event. About $358 million USD in damage resulted.
The Whittier Narrows earthquake along with two other events, the 1983 Coalinga earthquake, M 6.5; and the 1994 Northridge earthquake, M6.7, brought blind thrusts to the attention of seismologists and policy makers. As a result other significant blind thrusts have been identified in southern California.
References
External links
- [NOAA images of earthquake damage]
- [SCEC page on Whittier Narrows earthquake]
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