The 1987 Whittier Narrows earthquake struck the southern San Gabriel Valley and surrounding communities of southern California at 7:42 a.m. (PDT) 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 was in the town of Rosemead, California, at a depth of 9.5 kilometers (5.9 mi).
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.[1]
A magnitude 5.6[2] strike-slip aftershock occurred three days later, on October 4, causing additional damage, and one additional death.
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 the footings for a high tension power tower north of Pasadena, California. Lupe Elias-Exposito was killed when a concrete slab fell on her as she, her sister and a friend were exiting a parking structure at California State University, Los Angeles. Five other deaths are attributed indirectly to the event. About $358 million USD in damage resulted.[3]
The Whittier Narrows earthquake along with two other events - the 1983 Coalinga earthquake, and the 1994 Northridge earthquake, brought blind thrusts to the attention of seismologists and policy makers. As a result, other significant blind thrusts have been identified in Southern California.
[edit] See also
[edit] References
- ^ Shaw, John H.; Shearer, Peter M.. "A Blind-Thrust Fault Beneath Metropolitan Los Angeles Identified from Seismic Reflection Profiles and Precise Earthquake Locations". Harvard University Structural Geology and Tectonics. http://structure.harvard.edu/sgat/SGATfault.html. Retrieved April 27, 2006. [dead link]
- ^ http://earthquake.usgs.gov/regional/states/events/1987_10_04.php
- ^ Rowshandel, B.; Reichle, M.; Wills, C.; Cao, T.; Petersen, M.; Branum, D.; Davis, J. (April 11, 2006). "Estimation of Future Earthquake Losses in California". California Geological Survey. http://www.consrv.ca.gov/cgs/rghm/loss/index.htm. Retrieved April 27, 2006.
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Significant California earthquakes
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Very Large
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Large
(6.0-6.9) |
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Moderate
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United States
