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View Full Version : "Temblor Could Disturb Other Faults, Scientists Say."



megimoo
04-05-2010, 06:36 PM
The 7.2-magnitude earthquake that rippled through San Diego County and Baja California yesterday was noticeably long (up to a minute) and widely felt (as far away as Las Vegas and Phoenix), but the real import may be what the shaking bodes for California. “Any quake of this size seems to pass some kind of threshold where it’s large enough to disturb or trigger other faults,” said Pat Abbott, a professor emeritus of geology at San Diego State University. “In cases like this, that often means increasing stress on other faults,

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“Any quake of this size seems to pass some kind of threshold where it’s large enough to disturb or trigger other faults,” said Pat Abbott, a professor emeritus of geology at San Diego State University. “In cases like this, that often means increasing stress on other faults, which makes them more prone to movement. The energy seems to be moving northward toward the San Andreas Fault. I don’t want to anthropomorphize, but it’s like this quake was goading the San Andreas.”

snip

It remains to be seen how the 810-mile San Andreas Fault was affected by yesterday’s temblors. The southern section of the fault worries scientists because it has not ruptured in more than 300 years.

A 2008 study estimated the probability of a magnitude-6.7 or greater quake occurring in California within the next 30 years at 99 percent. The probability of one that is 7.5 or larger was set at 46 percent — and would most likely happen in the southern half of the state.

Easter Sunday’s 7.2 temblor was preceded by a handful of smaller quakes that began Wednesday, with the last happening just six minutes before the big jolt.

“Obviously, these now look like they were foreshocks,” said Nancy King, a geophysicist for the U.S. Geological Survey.

Not surprisingly, the 7.2-magnitude shake was followed by dozens of aftershocks and perhaps independent quakes that were triggered on other faults. Most of the subsequent shaking measured in the magnitude 3 to 4 range, though at least one temblor reached 5.4.

The fault or faults that produced the 7.2 quake, which started at 3:40 p.m. PDT, had its epicenter 108 miles east-southeast of Tijuana in Baja California. The region is riven by numerous faults.


http://www.signonsandiego.com/news/2010/apr/05/temblor-could-disturb-faults-scientists-say/

Gingersnap
04-06-2010, 10:10 AM
Interesting. I'll bet the guys at Rapture Ready are pretty excited. :D