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May 26, 2006

Strange But True!

Q. News is that scientists have learned how to switch earthquakes “off” and “on.” So why not switch off the fault that might bring the Big One to San Francisco?

A. The largest recorded quake was in Chile in 1960, where a slab of rock 800-by-200 kilometers slipped 21 meters past the adjacent rock, magnitude 9.5, says Nigel Calder in “Magic Universe.” Micro-earthquakes, with rock slippage or “creep” measured in millimeters, rank at magnitude 2 — undetectable by people or distant seismometers. But the little ones can grow into big ones, reasoned Hiroo Kanamori, at Tokyo University and Caltech. Since there are 100,000 times more quakes of magnitude 2 than 7, predicting the big ones is bound to be uncertain, as when forecasters failed to warn of the deadly Kobe earthquake in Japan in 1995.


 
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