'Violent' shaking at Napa earthquake epicenter rivaled Northridge

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Cellar worker Adam Craig, 36, of Napa works to clear the rubble at the Kieu Hoang Winery, one of several in the area that were damaged by the earthquake. (Rick Loomis / Los Angeles Times)

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Cellar workers work to clean up the Kieu Hoang Winery, one of several in the area that were damaged by the 6.0 temblor. (Rick Loomis / Los Angeles Times)

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Vickie Katsubayashi looks at a red-tagged home near downtown Napa. (Luis Sinco / Los Angeles Times)

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A home in Napa was damaged by Sunday’s 6.0-magnitude earthquake. (Alvin Jornada / EPA)

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A crack in the pavement cuts across a street in a neighborhood of Napa that was affected by Sunday’s quake. (Luis Sinco / Los Angeles Times)

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Bay Area Home Depot employees join a volunteer cleanup effort in downtown Napa. (Luis Sinco / Los Angeles Times)

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Bay Area Home Depot employees help with volunteer cleanup efforts in downtown Napa. (Luis Sinco / Los Angeles Times)

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Four homes at Napa Valley Mobile Home Park in Napa were destroyed by a fire triggered by the 6.0-magnitude earthquake that struck early Sunday. Two other homes were badly charred by the fire, while many were knocked off their foundations by the temblor. (Luis Sinco / Los Angeles Times)

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Karl Luchsinger recovers a child’s car seat from a vehicle after a carport collapsed in the Napa earthquake. (Josh Edelson / AFP Getty Images)

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Gin Betourne, 56, uses a candle for light after a 6.0 quake caused a power outage in her Napa, Calif., neighborhood. The quake damaged the chimney in the house she has lived in for six months. (Rick Loomis / Los Angeles Times)

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Maria Hanks, 50, and her husband Brad, 53, sit in candlelight after spending much of the day cleaning up the damage around their house. They lost power after a 6.0 quake struck and it had still not come back on by nightfall on Sunday evening. (Rick Loomis / Los Angeles Times)

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Cars sit under a carport at Charter Oaks Apartments in Napa that collapsed in Sunday’s earthquake. (Rick Loomis / Los Angeles Times)

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The remains of one of four mobile homes destroyed by fire at Napa Valley Mobile Home Park in Napa after the earthquake. The community was left without water and power. (Luis Sinco / Los Angeles Times)

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Phil Tessier of Napa helps Tim and Ann Whitlock move out of their home on Twin Oaks Drive after it was heavily damaged by the quake. About 100 people from their church, Grace Church of Napa, pitched in. “Who says you can’t move in six hours? It can be done,” Ann Whitlock said. (Rick Loomis / Los Angeles Times)

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One of the mobile homes destroyed by fire at Napa Valley Mobile Home Park in Napa. (Luis Sinco / Los Angeles Times)

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Scott Whitlock walks on a stretch of buckled sidewalk while helping his parents move out of their damaged home in Napa. (Rick Loomis / Los Angeles Times)

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Dan Kavarian, chief building official for the city of Napa, walks around the downtown area red-tagging building that were deemed unsafe after a 6.0 earthquake hit the area early Sunday. The quake damaged several buildings and caused several injuries. (Rick Loomis / Los Angeles Times)

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A 6.0 earthquake sent bricks falling from a Napa business onto a car early Sunday. (Rick Loomis / Los Angeles Times)

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People gather in downtown Napa to view the damage to buildings from a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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A close-up view of damage to a building caused by a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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Dan Kavarian, chief building official for the city of Napa, posts a yellow tag allowing limited access on a building damaged in a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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Windows at the post office in downtown Napa were shattered in a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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Bricks that fell from a building in Napa caused substantial damage to a car parked next to it during a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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The post office in downtown Napa suffered damage to its brick walls and windows in a 6.0-magnitude earthquake early Sunday. (Rick Loomis / Los Angeles Times)

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Gurbeer Singh cleans up fallen merchandise at a 7-Eleven store in American Canyon, Calif., after Sunday morning’s 6.0 earthquake. (Ben Margot / Associated Press)

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With spilled wine covering the floor, winemaker Tom Montgomery views damage caused by Sunday’s earthquake at B.R. Cohn Winery’s barrel storage facility in Napa, Calif. (Eric Risberg / Associated Press)

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Steve Brody inspects damage to his mobile home in Napa, Calif., after Sunday’s magnitude-6.0 earthquake. (Ben Margot / Associated Press)

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Bottles are strewn on the floor of the Bloom Hair Salon in Napa, Calif., after a magnitude-6.0 earthquake centered nearby. (Evan Wagstaff / Los Angeles Times)

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A home in Napa, Calif., that was badly damaged in the earthquake. (Evan Wagstaff / Los Angeles Times)

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A Napa, Calif., building housing a tasting room suffered significant damage in the earthquake. (Evan Wagstaff / Los Angeles Times)

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Broken bottles lie on the floor of an oil and vinegar store in Napa, Calif., after a 6.0-magnitude earthquake centered nearby. (Evan Wagstaff / Los Angeles Times)

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Napa County, Calif., firefighters spray foam on hot spots from a fire at a mobile home park in Napa after Sunday morning’s 6.0 earthquake. (Justin Sullivan / Getty Images)

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Jean Meehan looks over the damage to her JHM Stamp and Collectibles store in Napa, Calif., after Sunday morning’s 6.0 earthquake. (Eric Risberg / Associated Press)

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A building in Napa, Calif., is badly damaged after a 6.0 earthquake. (Justin Sullivan / Getty Images)

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Police officers exit a damaged building in Napa, Calif., after Sunday morning’s 6.0 earthquake. (Justin Sullivan / Getty Images)

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A woman looks at the damaged windows of the main post office in Napa, Calif., after Sunday morning’s earthquake. (Eric Risberg / Associated Press)

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The top corner of a building is exposed after Sunday morning’s 6.0 earthquake centered near Napa, Calif. (Eric Risberg / Associated Press)

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Bricks and fallen rubble cover a car parked near the old courthouse in Napa, Calif., after Sunday morning’s 6.0 quake. (Eric Risberg / Associated Press)

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Bricks can be seen in the street after a building was damaged during Sunday morning’s earthquake centered near Napa, Calif. (Ellen Knickmeyer / Associated Press)

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Residents survey the damage to a historic building in downtown Napa after a 6.0 magnitude earthquake hit the San Francisco Bay Area at 3:20 a.m. (Peter DaSilva / EPA)

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Store owners stand near broken glass in downtown Napa, Calif., after a 6.0 earthquake hit the San Francisco Bay Area early Sunday. (Peter DaSilva / EPA)

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Residents survey the damage to buildings in downtown Napa, Calif., after Sunday morning’s 6.0 quake. (Peter DaSilva / EPA)

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A man sweeps broken glass from store windows in Napa, Calif., after Sunday morning’s 6.0 earthquake. (Justin Sullivan / Getty Images)

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A resident checks out damage to a building at 3rd and Brown streets in Napa, Calif., after Sunday’s 6.0 quake. (Lyall Davenport / Associated Press)

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A CHP officer directs traffic away from a buckled section of California 12 after Sunday’s quake, which was centered near Napa. (Peter DaSilva / EPA)

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Napa, Calif., residents in bathrobes check out damage on their street after Sunday’s quake. (Justin Sullivan / Getty Images)

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Caltrans crews assess damage to a California 37 overpass in Vallejo after Sunday morning’s 6.0 quake. (Lee Romney / Los Angeles Times)

By Rong-Gong Lin IIStaff Writer

Aug. 26, 2014 8:20 AM PT

The intensity of shaking felt during Sunday’s magnitude-6.0 earthquake centered in Napa appears to have rivaled the motion felt at the epicenter of the Northridge magnitude-6.6 earthquake in 1994.

An estimate posted on the U.S. Geological Survey’s website put the Napa earthquake’s shaking intensity as level IX, which is classified as “violent” perceived shaking at the epicenter. There is only one level intensity higher than level IX, which is level X, which would be classified as extreme.

The perceived shaking during the Northridge quake was also a level IX.

Intensity of shaking is different than the magnitude, which is a number that represents total energy released during an earthquake.

It’s possible, however, that the intensity level could be downgraded later by the USGS, said state geologist John Parrish.

It’s important to point out that there was far more land that suffered from intensity IX shaking during the Northridge earthquake than in the Napa area, Parrish said.

“There has been substantially less damage in the Napa area than there was at Northridge,” Parrish said.

A day after the Napa temblor, inspectors had deemed 70 buildings here uninhabitable. The number of people treated for injuries had risen to 208, and schools remained closed. The Northridge quake was much more destructive and killed about killing about 60.

Napa residents described the shaking Sunday morning as so violent, they described struggling to get out of bed.