Residents of northern California are bracing for aftershocks after a magnitude 6.0 earthquake hit near Napa Valley Sunday, injuring at least 172 people and causing extensive damage, including fires sparked by burst gas lines, in the largest tremor to rock the Bay Area since the magnitude 6.9 Loma Prieta quake in 1989.
Aftershocks were expected to continue for several weeks, though State Geologist John Parrish told the Associated Press that they would decrease in magnitude and it was unlikely that there would be a large follow-up earthquake. Still, he warned people to be careful because buildings that were damaged by the quake were now more susceptible to collapse from aftershocks.
The U.S. Geological Survey says the tremor struck just before 3:30 a.m. Sunday local time about 10 miles northwest of American Canyon, which is about 6 miles southwest of Napa.
Of the 172 patients admitted to Queen of the Valley Medical Center in Napa, 13 were admitted to the hospital with broken bones and respiratory or cardiac conditions, while the rest were treated and released for less severe injuries, hospital president Walt Mickens said at a news conference Sunday evening.
Only one patient remains in the hospital in critical condition while another, a 13-year-old boy, was airlifted to another trauma center in critical condition after pieces of the fireplace at his home collapsed onto him, Mickens said. The boy is now listed in serious condition.
The most common injuries were from household items falling off of walls or shelves onto people or from those who stepped on debris in their homes, he said.
Mickens announced earlier Sunday that 120 people had been treated at the hospital, but that number rose as dozens of people got injured while cleaning up after the quake, he said.
Napa City Manager Mike Parness said the city declared a local emergency at 8:59 a.m. California time, which is the first step in getting more help from the state.
Pacific Gas & Electric said that 2,200 customers were without power as of late Sunday evening and said the utility hoped to have power restored to all customers by Monday morning. A spokesman said that approximately 70,000 customers in Sonoma and Napa counties lost power during the earthquake.
Mark Ghilarducci, director of the California Governor's Office of Emergency Services, said about 90 to 100 homes were deemed not habitable. He said the next step was to continue damage assessments and get a cost estimate for potential federal assistance.
Officials said they were still assessing buildings in the area.
A Red Cross evacuation center was set up at a high school, and crews were assessing damage to homes and roadways.
Authorities said Sunday evening that all bridges responded well to the earthquake.
John Callahan of the Napa City Fire Department said at one point Sunday there were a half-dozen multiple structure fires. One was at a mobile home park where four mobile homes have been destroyed by fire, and two others suffered major damage.
Public Works Director Jack LaRochelle assured residents the water has not been contaminated.
“The water is safe to drink,” he said. LaRochelle said that more than 60 water mains have been damaged; 20 have been turned off. He said none of the larger transmission lines had been damaged.
Napa Fire Chief Mike Randolph said firefighters were continuing to assess the damage to buildings in the downtown area, and the department was busy answering more than 100 calls reporting the smell of natural gas. That's "our primary attention right now," he said.
A number of buildings are damaged during the quake, but no number on how many was reported.
The city’s 911 emergency call system was maxed out, according to Napa Police Department operations captain Steve Potter, but he said there have been no reports of major disturbances. “We have relative calm for this magnitude of an earthquake,” he said.
Jennifer Jones Lee, who lives in the earthquake area, told Fox News the tremor “felt like someone just picked up the house, shook it for a while, then dropped it. It was incredibly violent.”
Arik Housley, who owns two grocery stores in the area, said he was awakened at about 3:30 a.m. by the shaking. “It was very jolting and probably went for 20 seconds . . . it was shaking pretty good,” said Housley, whose brother is Fox News senior correspondent Adam Housley.
Arik Housley said he passed a mobile home park where multiple fires could be seen as he drove to one of his stores to assess the damage. Housley said the shelving in his store had moved 2 feet to 3 feet from the wall, and much of his inventory had fallen to the floor, including $200 bottles of wine. Many merchants in the area forgo earthquake insurance because it’s too expensive, he said. A quake about 14 years ago resulted in about $30,000 in damage, he told Fox News, and speculated the current damage would be in excess of $100,000.
"There's collapses, fires," said Napa Fire Capt. Doug Bridewell, standing in front of large pieces of masonry that broke loose from a turn-of-the-century office building where a fire had just been extinguished. "That's the worst shaking I've ever been in."
Bridewell said he had to climb over fallen furniture in his own home to check on his family before reporting to duty.
The tremor set off car alarms and had residents of neighboring Sonoma County running out of their houses in the middle of night.
The USGS says the depth of the earthquake was just less than 7 miles, and numerous small aftershocks have occurred in the Napa wine country.
Aftershocks were expected to continue for several weeks, though State Geologist John Parrish said they would decrease in magnitude and it was unlikely that there would be a large follow-up earthquake. Still, he warned people to be careful because buildings that were damaged by the quake were now more susceptible to collapse from aftershocks.
“There’s fires, debris all over the streets, everywhere,” Napa resident Karen Hunt earlier told “Fox & Friends.”
Hunt said her husband, who is an engineer, shut off the gas line to their home to guard against explosions, then went to neighbors’ homes to do the same.
“Right now we’re just waiting for the aftershocks,” she said. She said she had not felt any, but reportedly there have been two, one at magnitude 2.5.
Hunt has said she has felt other earthquakes, but “this is way on top of anything I’ve ever felt.”
Hunt, who has lived in Napa since 1996, owns a winery. She said she heard from her partner that her 2011 and 2012 vintages had been destroyed.
“That’s pretty devastating if that’s the case,” she said.
Sunday's quake was felt widely throughout the region. People reported feeling it more than 200 miles south of Napa and as far east as the Nevada border. Amtrak suspended its train service through the Bay Area so tracks could be inspected.
California Highway Patrol Officer Kevin Bartlett said cracks and damage to pavement closed the westbound Interstate 80 connector to westbound State Route 37 in Vallejo and westbound State Route 37 at the Sonoma off ramp. He said there hadn't been reports of injuries or people stranded in their cars, but there were numerous cases of flat tires from motorists driving over damaged roads.
Thousands of small earthquakes occur in California each year, providing scientists with clear indications of places where faults cut the Earth's crust. There were 4,895 earthquakes in California between 1974 and 2003 with a magnitude of 3.5 or greater (about 163 per year).
The Associated Press contributed to this report.