Some people in the San Francisco Bay area were awakened by an earthquake, though there have been no damage reports. The USGS' report is here.
One 2.9-magnitude struck at 5:33 a.m., with another 4.0-magnitude following only eight seconds later near El Cerrito. A U.S. Geological Survey computer-generated report says the magnitude-4.0 quake struck at 5:33 a.m. Monday.
There was a 2.2-magnitude aftershock at 6:03 a.m. near the same location.
BART is reporting no delay, but they will run a system check, which usually causes a brief delay.
Seismologists said the quake appeared to occur on the Hayward Fault, a seismically active fault that runs along the eastern San Francisco Bay. A 2003 USGS report said the Hayward Fault had the highest chance -- 27 percent -- of producing a large earthquake of magnitude-6.7 or higher in the Bay Area within 30 years.
Viewers from all over the Bay Area are posting that they felt the earthquake on our Facebook page. Some claim to have felt it as far west as Half Moon Bay and as far south as Palo Alto.
A California Highway Patrol dispatcher says the quake was felt throughout San Francisco and as far south as Palo Alto.
Oakland Police Dispatcher sid she felt the quake. Officer McDonald with the Oakland PD said told Bay City News it was a jolt and then a series of smaller rumblings which lasted a few seconds.
Nothing came off the walls, but their lockers rattled a bit. No initial reports of injuries or damage, but their dispatch center took a number of calls.
-- The Associated Press contributed to this report.