The U.S. Geological Survey's preliminary report put the quake at a 4.0-magnitude.The temblor's epicenter was near Alamo, Calif., about 28 miles east of San Francisco.
There were no immediate reports of damage or injuries in Alamo or surrounding communities, said Contra Costa County Sheriff's spokesman Jimmy Lee.
The quake hit just after 9 p.m. and could be felt throughout the region.
Fans at the San Francisco Giants' waterfront ballpark felt a jolt during the game with the Pittsburgh Pirates, but there was no interruption of play.
