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Minor Quake Shakes Bay Area Precede WASHINGTON.

December 11, 1986

FREMONT, Calif. (AP) _ A minor earthquake shook the San Francisco Bay area this morning, but no damage or injury was reported.

The quake struck at 6:18 a.m. and was estimated as having a magnitude between 3.8 and 4.0 on the Richter scale, suggesting it was capable of slight to moderate damage. However, it went unnoticed by many area residents.

The earthquake was assigned a magnitude of 3.9 on the open-ended Richter scale by the Seismographic Stations at the University of California at Berkeley and 3.8 by the state Department of Water Resources.

The U.S. Geological Survey’s earthquake scientists in Golden, Colo., said the quake had a magnitude of 4.0 and was centered 12 miles northeast of Fremont.

Berkeley research associate Bob Darragh said the quake apparently struck along an unnamed fault east of the Calaveras Fault.

The Richter scale gauges energy released by an earthquake as measured by ground motion recorded on a seismograph. Every increase of one number means that the ground motion is 10 times greater.

A quake with a magnitude of 4 can cause moderate damage in a populated area, a quake of magnitude 5 considerable damage, a magnitude 6 quake severe damage, one of magnitude 7 widespread, heavy damage and a magnitude 8 quake, a ″great″ earthquake capable of tremendous damage.

A quake of magnitude 2 is the smallest normally felt by humans.

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