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Posted: March 20,
2006 |
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 San Andreas Fault |
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Probability for one or more magnitude 6.7 or greater earthquakes from 2003 to 2032: 21 % |
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The San Andreas Fault is the boundary where the North American plate on the east and the Pacific Plate on the west meet along the United States' west coast. Known as a "master" fault because of the complex web of sub faults that extend from it, the San Andreas stretches 800 miles from northern California to the south near San Bernardino. The fault is believed to be about 15 million to 20 million years old and extends at least 10 miles into the earth. Because rocks on each side of the fault inch past each other horizontally and to the right, the fault is considered a right-lateral strike-slip.
The largest earthquakes to rupture the San Andreas Fault occurred on Jan. 9, 1857 and April 18, 1906, both about a magnitude 7.8. The last major earthquake was the Loma Prieta on Oct. 17, 1989, a magnitude 6.9. |
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