CUPERTINO (CBS SF)  — The U.S. Geological Survey reports a 2.2 magnitude earthquake struck after 11 a.m. in Silicon Valley, shaking the South Bay for the second time, after a 4.2 magnitude quake hit Coalinga this morning.

The lunchtime tremor hit at a depth of "zero," which is not common. Deeper quakes are less noticeable while a shallow quake--in the 0 to 40 mile depth range--can feel much stronger than their actual reported magnitude. Quakes just below the earth's surface, in the 0 to 10 miles range, can cause even more damage at lower magnitudes.

The epicenter of the small tremor was two miles south-southwest of Loyola, and four miles west of Cupertino, or five miles from Los Altos.

Earlier today, a stronger 4.2 quake hit Coalinga in the central valley.

COMPLETE QUAKE COVERAGE: CBS Earthquake Resource Center

DID YOU FEEL IT?: USGS Shake Map For Northern California
LIVE QUAKE MAP: Track Real-Time Hot Spots
BAY AREA FAULTS: Interactive Map Of Local Faults

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