The quake struck at 2:39 a.m. about 2 miles (3 kilometers) from Berkeley, just across the bay from San Francisco, according to the US Geological Survey. The magnitude was revised after it was initially reported as magnitude 4.5. It happened at a depth of 8 miles (13 kilometers).

Social media posts showed people were awakened some 40 miles (64 kilometers) to the north and south, but there were no immediate reports of damage or injuries.

"Felt like a big truck drove into the building or something blew up downstairs. It just rocked the room and bed like two or three times quickly with a decently loud rumble in North Berkeley," Dale Fest wrote on the San Francisco Chronicle's Facebook page .

Bay Area Rapid Transit said it had checked tracks for damage and found no problems. Early delays in train service were cleared up by 5:30 a.m., the agency said.

Jack Boatwright, a geophysicist with the USGS Earthquake Science Center in Menlo Park, said the shaking from the quake "seemed a little weak, about half as strong as what you would expect."

He told the Chronicle that by 4:15 a.m., there had been no aftershocks, which he called "a good sign. It may mean less likelihood of a larger earthquake to follow."