6.0 quake rocks Northern California followed by more than 30 aftershocks. Jolt felt in Bay Area

In Mono County, Sheriff Ingrid Braun was in her Bridgeport office when the building started shaking.

“It reminded me a little bit of the Northridge Earthquake,” said Braun, who said she lived in Santa Clarita when the massive quake struck in 1994. “It just kept rolling and you could see the door frame swaying back and forth.”

Shaking was felt in Walker, Coleville and throughout the county, Braun said, but there were no reports of significant damage as of 5 p.m.

But the quake and aftershocks caused a rockslide at Highway 395 at a campground called Chris Flat in Walker Canyon in Mono County, which is a popular destination for fly-fishing, Braun said. The rockslide closed that portion of the highway, and officials with Caltrans and California Highway Patrol were at the scene on Thursday afternoon. There were no reports of injuries in that area, Braun said.

Braun said she has been in contact with officials with the California Governor’s Office of Emergency Services and plans to keep them updated on conditions in Mono County.

“We’re really fortunate and happy that so far the damage has been minimal and we haven’t had any reports of injuries,” Braun said.

In Smith Valley, Nevada, Sue Wood was serving plates of hamburgers to customers at Smith Valley’s Buckboard General Store when she heard a booming crack. Moments later, the merchandise on the store’s shelves began shaking and the floor rolled beneath Wood’s feet.

“It shook us good,” Wood said Thursday afternoon, minutes after the upheaval subsided.

The quake lasted about 20 seconds, she said, leaving customers in the sparsely populated desert outpost rattled, but unharmed. Wood hadn’t heard of any injuries or structural damage, but called the episode “scary.”

Among the aftershocks, six exceeded magnitude 4.0.

The U.S. Geological Survey said it expects more aftershocks to continue around the area of the 6.0 main quake, and officials said the quake could be part of a “sequence” that could have even larger quakes.

Seismologists were forecasting that over the next week, there is a 6% chance of an aftershock that is larger than magnitude 6.0.

The area east of the Sierra Nevada is a “very active” earthquake zone, owing to its position on the North American tectonic plate, said Sarah Minson, a research geophysicist with the U.S. Geological Survey.

The California-Nevada border region is being “pulled like taffy” as California inches west toward the Pacific Ocean, Minton said, which gives the area its distinctivly hilly topography and makes it highly prone to earthquakes and aftershocks.

The USGS initially reported that a 4.8 quake had struck east of Stockton in San Joaquin County but then removed the quake from its list. The 6.0 quake was initially registered at 6.2, downgraded to 5.9 and then adjusted to 6.0 after reviews by seismologists.

People in the Bay Area reported feeling the shaking.

Click here for The Chronicle’s Earthquake Tracker.