The United States Geological Survey (USGS) said the quakes, eight minutes apart, began at about 7:10 a.m. Pacific time Wednesday. The first registered 3.1 on the Richter scale, while the second was a 5.4 magnitude quake. The tremors were centered in the San Juan Bautista area, about 80 miles southeast of San Francisco.
The USGS reported that more than a dozen aftershocks occurred. The largest aftershock registered 3.0 on the Richter scale, while nine others registered above 2.0.
The quakes caused no serious injuries, but they were powerful enough to open at least three cracks in Highway 101 in San Benito County and on State Highway 156 near Hollister, officials said. Highway authorities were most concerned about possible damage to overhead structures and were checking overpasses in the affected areas, Correspondent Len Ramirez of CBS News Station KPIX-TV in San Francisco reports.
San Juan Bautista at the quakes' epicenter is a picturesque town of 1,570 residents graced by a Spanish mission, which was featured in the Alfred Hitchcock movie Vertigo. Both the town and the mission sustained little damage.
"I feel this is a small price to pay for being here, for having a shop in San Juan Bautista," said shop owner Eileen Rosa.
There were no immediate reports of injuries from the quakes, which lasted a few seconds.
"My couch was moving across the room. It felt like it moved four inches, one inch at a time," said Jessica Qualley of San Francisco.
"It seemed to be a pretty good one," said Pat Walker, manager of the El Dorado Motel in Salinas, a few miles southwest of the epicenter. "Everything kind of shook for a while, and we just rode it out."
People felt the quake as far away as Watsonville, 70 miles to the south, and Alameda.
Bay Area Rapid Transit trains were halted to allow transit officials to check for damage. BART officials said they restored service after deciding that train tracks were safe.
Pat Jorgensen, a spokeswoman for the USGS, said the earthquake occurred along the San Andreas fault and was one of the larger quakes to occur in that area. Jorgensen said the earthquake was not unusual for the seismically active area.