Second Earthquake Hits Bay Area Thursday Night

The U.S. Geological Survey has downgraded last night's 8:16 p.m. earthquake from its original preliminary magnitude of 4.2, to 3.9 a short time later, and now experts report it was a 3.8-magnitude tremor.

The quake struck was centered about one mile east of Berkley with a depth of 6 miles, the USGS said.

BART stopped all trains when the quake occurred and began track inspection. No injuries or damage was reported, according to BART spokesman Jim Allison.

The temblor created a large jolt in San Francisco, including the Civic Center area, Nob Hill, Richmond District, and Haight-Ashbury neighborhood, and was felt throughout the region including the San Mateo County Coast, Danville, Santa Cruz, Palo Alto, Oakland and Berkeley.

A 4.0-magnitude earthquake struck the area at 2:41 p.m. today. That quake was centered about two miles east-southeast of Berkeley, and had a depth of 6.1 miles, according to the USGS.

After Thursday's first quake, Keith Knudsen, deputy director of the USGS Earthquake Science Center in Menlo Park, said it was a standard Hayward Fault Line quake.

He said the temblor was of the typical "strike-slip" variety, in which two sides of the fault slide horizontally, he said.

Thursday's earthquakes occurred on the same day as the Great California ShakeOut, a statewide drill in which millions of Californians practiced ducking and covering at 10:20 a.m.

San Francisco Mayor Ed Lee on Thursday urged all Bay Area residents to visit www.72hours.org for emergency planning resources and tips.

- Bay City News

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