NorCal Earthquake Swarm: 6.0 Temblor Spurs Dozens Of Aftershocks

WALKER, CA — A 6.0 earthquake that struck near the Northern California-Nevada border Thursday sent items flying off shelves and triggered rock slides. A swarm of aftershocks also followed the quake and kept residents on edge Friday.

The larger quake, which was originally recorded at 5.9 and later revised to 6.0, was felt as far away as Las Vegas and the San Francisco Bay Area. Residents of Sacramento County and Carson City, Nevada, also felt the quake and some of its residual aftershocks, authorities said.

The 6.0 temblor, reported just before 4 p.m., was centered just south of Lake Tahoe near Walker in Mono County. The shaking sent rocks tumbling into roadways in Walker and Coleville, causing road closures and traffic delays.

Thursday's larger quake was followed by dozens of aftershocks, including at least a half-dozen of magnitude 4 or above, according to the U.S. Geological Survey. All aftershocks felt on Friday as of noon were magnitude 3.7 and below.

Aftershocks were expected to persist for several days, officials said.

The Thursday temblor was the largest earthquake recorded in the area since a 6.1 magnitude quake shook the area near the state border in 1994.

State emergency crews worked through the night to survey for damage. Minor road damage was found, but there weren't any significant effects to infrastructure, said Brian Ferguson, spokesman for the California governor’s Office of Emergency Services.

"We were relieved it wasn’t anything more substantial," he told The Associated Press.

The California Department of Transportation closed Highway 395 from Bridgeport in Mono County to the Nevada state line Thursday as crews worked to clear rock slides, KCRA reported. There were no reports of significant damage, and the highway has since reopened.

Some vehicles were hit by falling rocks, but no injuries were reported, the California Highway Patrol said.

California's emergency services agency confirmed that the quake did not cause any significant roadway or infrastructure damage. But residents of both California and Nevada reported the severity of the quake.

"Our whole entire store was shaking," said Brittany Oswald, who works at Smith's Food and Drug in Gardnerville, Nevada, where boxes reportedly flew off shelves. "I just stood there and held onto a table and waited for it to end."

Sally Rosen, owner of the Walker Burger restaurant, told the AP Friday that she did not sleep well.

“There were aftershocks all night. There were a couple that were very strong in the middle of the night. And I even felt one this morning at the restaurant,” Rosen said. Nothing compared to the initial jolt and heavy shaking from the day before, she added: “It was the most intense, violent kind of shaking” she’d ever felt, she said.

There are 15,700 known faults in California, and more than 500 are active, according to the Earthquake Authority. In Mono County, near where Thursday's quake struck, the region has "tremendous geological forces," from the steep slope of Mt. Whitney to the vast Owens Valley in Inyo County.

The area is also home to the Owens Valley Fault, which has caused devastating earthquakes in the past. The Eastern California Shear Zone, also in that area, runs from the Gulf of California through the Mojave Desert-Death Valley into Nevada — regions of increased seismic activity, according to the Earthquake Authority.

The American Red Cross recommended the following earthquake safety tips.

• Become aware of fire evacuation and earthquake safety plans for all of the buildings you occupy.
• Pick safe places in each room of your home, workplace or school. A safe place could be under a piece of furniture or against an interior wall away from windows, bookcases or tall furniture that could fall on you.
• Practice "drop, cover and hold on" in each safe place. If you do not have sturdy furniture to hold onto, sit on the floor next to an interior wall, and cover your head and neck with your arms.
• Keep a flashlight and sturdy shoes by each person's bed in case the earthquake strikes in the middle of the night.
• Make sure your home is securely anchored to its foundation.
• Bolt and brace water heaters and gas appliances to wall studs.
• Bolt bookcases, china cabinets and other tall furniture to wall studs.
• Hang heavy items, such as pictures and mirrors, away from beds, couches and anywhere people sleep or sit.
• Brace overhead light fixtures.
• Install strong latches or bolts on cabinets. Large or heavy items should be closest to the floor.
• Learn how to shut off the gas valves in your home and keep a wrench handy for that purpose.
• Learn about your area's seismic building standards and land use codes before you begin new construction. Keep and maintain an emergency supplies kit in an easy-to-access location.

See Also:

• Earthquake Preparedness: Must-Have List
• Earthquake Preparedness For CA Pet Owners

The Associated Press contributed to this report.