A magnitude 6.0 earthquake near the California-Nevada border south of Lake Tahoe shook a large swath of the state Thursday afternoon, according to the U.S. Geological Survey.
The temblor hit at about 3:49 p.m. about 40 miles southeast of Lake Tahoe and 4 miles west-southwest of Walker at a depth of about 5 1/2 miles, USGS said.
The shaking was estimated to be very strong at the epicenter with the potential to cause moderate damage. People reported feeling it as far away as San Francisco Bay area and across the Central Valley from Chico to Bakersfield.
USGS had earlier listed the quake at magnitude 5.9, but hours later revised the figure up and said it was followed 30 seconds later by a 5.2 magnitude quake.
The two large quakes were followed by 40 aftershocks within three hours. By 10:30 p.m. there were a total of 76 aftershocks, including eight in the magnitude-4 range.
Former Caltech seismologist Lucy Jones said a large amount of aftershocks is common for the region.
“The ground was shaking pretty bad, and then everything started falling,” said Carolina Estrada, manager at the Walker Coffee Company. Syrup bottles broke, dishes fell to the ground and the roof of the shop caved in a bit.
The shaking lasted 30 seconds or more, she said.
“We ran out of the building,” Estrada said. But the shaking continued, and “boulders the size of cars” fell onto nearby U.S. 395, she said.
Cars were struck by rocks, but nobody was injured, the California Highway Patrol reported.
At one point, rockslides closed about 40 miles of the interstate, a major route through the northern Sierra Nevada, authorities said. Portions of the interstate were later reopened, but crews remained at the scene in case of aftershocks, according to the California Department of Transportation.
In Nevada, Reno City Hall was evacuated, Mayor Hillary Schieve told the Reno Gazette Journal. “It shook pretty good,” Schieve said.
The epicenter was near the Antelope Valley fault. The earthquake was the largest one recorded since a magnitude 6.1 earthquake struck the area in 1994.
“People in the area should expect aftershocks for days following an earthquake of this size,” said Jason Ballmann with the Southern California Earthquake Center at the University of Southern California. “We’ve already seen a pretty vigorous aftershock sequence.”
Ballman cautioned that reports of damage or injury might not be available for days because a lot of the shaking was felt in remote areas.
Sally Rosen, who owns a popular burger restaurant in Walker, near the epicenter, said her 2-year-old was napping in her arms in her home behind the restaurant when the earthquake hit.
“We felt the shaking of the building, and we didn’t know quite what it was at first,” she told KGO-TV in San Francisco. “It kept going, and it was pretty intense and scary, frankly. So we ran out of the house as fast as we could and ran to the restaurant because the first thought was, ‘Oh my goodness, we need to shut off the gas.’ ”
Cups and other items flew off the shelves, and oil splattered from the fryers, she said.
California emergency officials said the situation was “rapidly evolving” and more details were expected in the coming hours.
Preliminary reports had indicated two earthquakes striking 25 seconds but 100 miles apart. But the U.S. Geological Survey revised the shaking and removed the report of a magnitude 4.8 quake in Farmington, about five miles southeast of Stockton, the Sacramento Bee said.
Correction: This story has been updated to correct the spelling of the last name of Jason Ballmann at the Southern California Earthquake Center at USC.