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Earthquake Rattles East S.F. Bay Area

October 22, 1987

LIVERMORE, Calif. (AP) _ A moderate earthquake rattled the San Francisco Bay area Wednesday night, but officials said there were no immediate reports of damage or injuries.

″It was a pretty good jolt,″ said police dispatch clerk Dave Beason.

The quake struck at 8:48 p.m. and measured 4.1 on the Richter scale, according to Anthony Lomax of the University of California Seismographic Stations in Berkeley.

The epicenter was 10 miles north of Livermore and about 35 miles east of Berkeley in a rural area on the southeast flank of 3,849-foot Mount Diablo, Lomax said.

The quake was felt throughout the area east of San Francisco Bay, and some San Francisco and San Jose residents also reported feeling it.

The Richter scale is a measure of ground motion as recorded on seismographs. Every increase of one number means a tenfold increase in magnitude. Thus, a reading of 7.5 reflects an earthquake 10 times stronger than one of 6.5.

An earthquake of 4 on the Richter scale can cause moderate damage.

The San Francisco earthquake on Aril 18, 1906, took place before the Richter scale was developed, but has since been calculated to have hit with a force of 8.3.