An earthquake of preliminary magnitude 3.4 hit Contra Costa County early Saturday morning.
The United States Geological Survey detected the quake at 12:25 a.m. with an epicenter 7.0 miles southwest of central Brentwood and a depth of 11.1 miles.
The fault that caused the quake was not immediately known, but the epicenter was 2.2 miles northeast of Greenville fault zone (Marsh Creek-Greenville section), according to the USGS fault database. Explore the major California faults on our map…