North Bay: Yep, that was a Quake You Felt
Updated 9:45 AM PST, Sun, Jul 12, 2009
The U.S. Geological Survey is reporting an earthquake with a preliminary magnitude of 3.0 struck this morning in Sonoma County.
According to the USGS, the earthquake struck at about 4:30 a.m. and had a depth of 1.7 miles.
The quake was centered two miles north of The Geysers and 11 miles east of Cloverdale, according to the USGS.
It was the second small quake to strike in the area this morning. A 2.3 earthquake also struck nearby at about 2:15 a.m.
That earthquake had a depth of 1.2 miles and was centered four miles east-southeast of The Geysers and 15 miles east of Cloverdale, according to the USGS.
Earlier this week scientists announced they have detected a spike in underground rumblings on a section of California's San Andreas Fault that produced a magnitude-7.8 earthquake in 1857.
What these mysterious vibrations say about future earthquakes is far from certain. But some think the deep tremors suggest underground stress may be building up faster than expected and may indicate an increased risk of a major quake.
Researchers at UC Berkeley monitored seismic activity on the fault's central section near Parkfield between July 2001 and February 2009 and recorded more than 2,000 tremors. The tremors lasted mere minutes to nearly half an hour.
Unlike earthquakes, tremors occur deeper below the surface and the shaking lasts longer.
Tremor episodes persist today. Though the frequency of tremors have declined since 2004, scientists are still concerned because they are still at a level that is twice as high as before the 2003 quake.
First Published: Jul 12, 2009 9:29 AM PST
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