A 3.6-magnitude earthquake shook Contra Costa County on Saturday night, according to the U.S. Geological Survey.
The quake struck about 2 miles south of Hercules just after 7 p.m. and had a 6-mile depth, according to the USGS.
A witness in Alameda felt her apartment building shake just after the quake began.
"I thought it was the Rapture," she said.
Harold Camping, founder of the Oakland-based Family Radio network, predicted earlier this year that the Rapture -- the ascension of millions of earth dwellers into heaven marked by a massive earthquake -- would take place Saturday.
The quake was 8 miles north of Berkeley and 9 miles south of Vallejo.