It was warm and muggy in the East Bay on Sunday afternoon, a feeling that some refer to as "earthquake weather."
At just before 3:30 p.m., a 2.5 magnitude earthquake struck about 6 miles east of the unincorporated community of Blackhawk, and about ¿7 miles south-southeast of Brentwood, according to preliminary reports from the U.S. Geological Survey. It was also about 11 miles north of Livermore and about 11 miles southeast of Clayton, but checks with residents and merchants there didn't turn up anyone who felt the small jolt.
No damage or injuries were reported. The temblor had a depth of about 10 miles, according to the USGS.
Earthquakes in the San Ramon Valley are common. Last November, a cluster of small earthquakes along the Calaveras Fault -- a 3.4 magnitude the largest -- hit the area over a period of seven days.
David P. Schwartz with the USGS said the San Ramon Valley "is one of the more highly seismic parts of the Bay Area with regard to the occurrence of small earthquakes."
-- Kristin J. Bender, Staff