Bay Area hit by 2 quakes on same day as national earthquake drill

The San Francisco Bay area was struck by two earthquakes Thursday with only six hours between them. The quakes came on the same day as the Great ShakeOut, a national event that encourages earthquake preparedness and emergency response drills.

The U.S. Geological Survey says a 4.0 quake hit near Berkeley Thursday afternoon and was followed by a magnitude 3.9 quake at about 8:16 that evening. The second quake occurred about two miles east of Berkeley.

The San Francisco Gate reports that the quakes occurred on the Hayward fault and that they were felt throughout the East Bay and San Francisco.

Berkeley police say they have no reports of damage or injuries from either quake.

According to the Gate, the second earthquake was actually an aftershock.

"When you have an area with such an active seismicity, it's hard to tell if you're really seeing an aftershock or if it's just a regular earthquake," geophysicist Rafael Abreu told the Gate. "You should be prepared for more earthquakes to happen, whether they're aftershocks or not."

Thursday's quakes come almost 22 years to the day after the Loma Prieta earthquake struck the Bay area during the 1989 World Series.

The magnitude-6.9 quake killed 63 people, injured almost 3,800 and caused up to $10 billion damage.