Did You Feel the Quake?

Did you feel the quake, Novato? Bay Area residents regained their footing after a 4.0-magnitude earthquake rattled the region Thursday afternoon.

The quake, which occurred at 2:41 p.m., was centered about two miles east-southeast of Berkeley, and had a depth of 6.1 miles, according to the U.S. Geological Survey.

The temblor created a large jolt in San Francisco's Civic Center area and was felt in parts of the region including Alamo, Sausalito, Clayton, San Leandro and Santa Cruz and a couple of small aftershocks centered in Berkeley, according to the USGS.

Berkeley police said they have not received any reports of damage or injuries but have gotten some calls about car and building alarms that were activated by the quake.

Staff members at the Rockridge Branch Library in Oakland said that a rumbling sound could be heard during the quake, which sent a few pieces of mounted artwork askew.

"It was very dramatic here — the building shakes every time a truck goes by — so everyone in the building noticed it," said Erica Siskind, a children's librarian.

She and a few parents in the children's reading area at the time began ushering a handful of children under nearby tables, but by then, the tremors had stopped. Further north at Saul's Restaurant and Deli in Berkeley, restaurant manager Taci Traverso said no glasses or dishware had broken, but that she and her co-workers felt and in some cases, heard, the shaking.

"I heard it coming," she said. "It's hard to describe, but I was sitting on the sidewalk and I felt a rumbling sound...before I felt the vibration."

The earthquake occurred on the same day as the Great California ShakeOut, a statewide drill in which millions of Californians practiced ducking and covering at 10:20 a.m. Thursday.

Oakland Unified School District spokesman Troy Flint said all 101 of the district's schools were scheduled to take part in the drill, which he said likely helped staff and students deal with the brief quake.

"It was interesting timing — it definitely reinforces the importance of these drills, even though people don't even always take them seriously," Flint said.

Students and faculty at the University of California at Berkeley also participated in the ShakeOut, sounding a siren across campus, school spokeswoman Janet Gilmore said.

The irony of an earthquake hitting on the same day as the statewide drill was not lost on Keith Knudsen, deputy director of the USGS Earthquake Science Center in Menlo Park, although he said the temblor was a standard Hayward Fault Line quake.

He said the temblor was of the typical "strike-slip" variety, in which two sides of the fault slide horizontally, he said.

The USGS released a preliminary earthquake measurement of 4.2 in the instants after the quake, then 3.9, before settling on the 4.0-magnitude reading later this afternoon.

Knudsen said that there is a roughly 5 percent chance that the afternoon quake could be a foreshock to a larger seismic event.

San Francisco Mayor Ed Lee released a statement about two hours after the quake, calling it "another reminder that we have to be prepared."

Lee urged all Bay Area residents to visit www.72hours.org for emergency planning resources and tips.

— Bay City News Service