The earthquake occurred at 9:35 a.m. and had a depth of 4 miles.
The quake was centered about 1 kilometer north-northwest of central San Pablo and 2 miles north of Richmond, according to the USGS.
The epicenter was located near San Pablo's Merritt Avenue, where Carmen Harrison lives.
"I was sitting in my kitchen and I was shaking in my chair," Harrison said.
She said the quake seemed big but caused no damage inside her home.
"I have a headache only," Harrison said. "It was a little scary, but everything's fine."
A 2.4-magnitude aftershock also struck in the same area at about 10:05 a.m., according to the USGS.
The initial temblor caused BART to briefly shut down train service to check for damage to the tracks, a BART employee said.
Trains were back up and running with residual delays of about 10 minutes as of 10:15 a.m., the employee said.
