BERKELEY, California (CBS) -- Another earthquake has jolted the San Francisco Bay area.
The U.S. Geological Survey says a quake with a preliminary magnitude of 3.9 hit at 8:16 p.m., about two miles east of Berkeley.
The earthquake Thursday night comes after a 4.0 earthquake hit in the same area nearly six hours earlier. Berkeley police say they have no reports of damage or injuries from either quake.
Earlier, a moderate earthquake shook the San Francisco Bay area Thursday afternoon, rattling residents who said it felt much stronger.
The quake, with a preliminary 4.0 magnitude, was centered near Berkeley, much closer to downtown San Francisco and Oakland than most quakes felt in the Bay Area. San Francisco police and officials at University of California, Berkeley, said they had no reports of injuries or damages.
The U.S. Geological Survey said the earthquake hit two miles southeast of Berkeley at 2:31 p.m. According to USGS maps, the quake was actually centered directly beneath UC Berkeley's campus.
Officials at UC Berkeley said they had not received any reports of damage or injuries. Tami Humphrey, director of a preschool just north of Berkeley, was outside with her students when the quake struck.
"We felt it pretty good. It felt like a drop and then a shake," she said. "The kids didn't even notice."
Officials at Bay Area Rapid Transit said the system's trains were delayed about 15 minutes as workers inspected tracks.
The quake was felt as a sharp jolt in the East Bay area and across the bay in San Francisco. Its vibrations were felt just hours after an annual, statewide earthquake preparedness drill, the "Great California ShakeOut."
More than 8 million people signed up to participate in the drill, practicing the recommended "drop, cover and hold on" technique for protecting oneself during a quake.
Thursday's jolt also came almost 22 years to the day after the Loma Prieta earthquake struck the Bay Area during the 1989 World Series. And it occurred on the same day that more than 8.5 million people signed up to participate in an annual earthquake drill in which people duck under desks and tables.