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article imageSwarm of minor quakes continues in eastern S.F. Bay Area

By Nathan Salant     Oct 29, 2015 in Environment
San Ramon - A swarm of small earthquakes continued to roll through the eastern San Francisco Bay Area this week as residents felt at least 10 quakes by 10 a.m. Tuesday morning.
Seismologists also reported a 3.2-magnitude quake, largest so far, struck Tuesday evening at 5:07 p.m., as the region's Calaveras Fault continued to relieve stress.
But earthquake experts reassured worried San Ramon Valley residents that the continuing quake activity was not considered unusual and did not suggest a larger quake was imminent, according to the San Francisco Chronicle newspaper.
Hundreds of quakes ranging in magnitude from 1.0 (nearly imperceptible) to slight (3.0) have been felt on the eastern shore of San Francisco Bay since the swarm began on Oct. 13.
No damage has been reported, the newspaper said.
San Ramon is a suburban city located 25 miles east of Oakland.
"The good news is that most of these earthquakes stay under magnitude 4,” Susan Garcia of the U.S. Geological Survey’s Earthquake Science Center in Menlo Park, Calif., said last week.
"An earthquake swarm is not unusual in that area,” Garcia said.
In fact, a smaller swarm of quakes hit the area last week, including a 3.4 temblor that could be felt as far north as Vallejo and as far south as Pleasanton, the newspaper said.
No damage was reported then, either.
A similar swarm hit San Ramon in 2003, the newspaper said.
The Calaveras Fault is considered a branch of the San Andreas Fault and generated a 6.5-magnitude quake in 1911.
The most-notable recent quake on the Calaveras Fault was a 6.2 shaker in 1984.
More about Earthquake, East Bay, California, San Francisco, San Ramon
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