Napa, Calif., residents were awakened at 3:20 a.m. on Sunday, Aug. 24, by a magnitude 6.0 earthquake that struck six miles southwest of the Northern California city, sending as many as 160 to the hospital, and causing widespread damage, including dozens of broken water mains and triggering six major fires. One person was still in critical condition Sunday evening.
The fires destroyed several mobile homes, and firefighters struggled with water pressure issues since a significant amount of pressure was lost because of the cracked and broken water mains. Most of the damage occurred in downtown Napa where the buildings are older.
There was also significant damage to roads, but the California Highway Patrol and California Department of Transportation found no damage to bridges. The Transportation Department also had dive teams checking local toll bridges but found no damage.
Gov. Jerry Brown declared a state of emergency as crews in Napa searched for unseen damage. “A lot of the damage in moderate earthquakes is unseen,” said Brad Alexander, chief of media relations for the California Office of Emergency Services (Cal OES). “It happens below ground, under buildings, in between walls, in the sewer systems. You have to get into the ground, into the infrastructure to see what’s going on.”
Alexander and Cal OES staff activated the state EOC near Sacramento at around 4:30 a.m. and remained throughout the evening to help coordinate efforts in the Napa area, including search and rescue. “We have the ability to task urban search and rescue teams to get to the impacted zones.” He said they had deployed three such teams in the area to search “floor to floor and door to door,” for anyone who may have been injured.
“Since it happened in the middle of the night there could have been janitorial staff or security personnel in a business and knocked unconscious,” Alexander said. “We want to make sure everyone was evacuated.”
Mark Ghilarducci, Cal OES director, was flown over the affected area to get an idea of the damage and said at a press conference Sunday afternoon that the quake was not as bad as it could have been. He said there was a lot of regional impact, including damage to single-family homes, fires and power outages, affecting 20,000 to 25,000 people.
There were 50 to 60 aftershocks up to magnitude 3.6, and aftershocks are expected to continue for weeks but at decreasing magnitudes. In the hour after an earthquake there’s a 54 percent chance of another large quake occurring but the likelihood diminishes as the hours pass.
The California National Guard called up its Northern California forces and sent them to armories if needed. They can supply search and rescue, water purification, security, logistics and aid communication.
There were no reports of damage in San Francisco, according to Francis Zamora of the city’s Department of Emergency Management. “We did a survey of the city’s major operational departments and found no damage,” Zamora said. “But we are ready and able to provide mutual aid if called upon, but so far no requests have been made.”
Ghilarducci said the state is a couple of years away from having an earthquake early warning system and noted pilot projects, including one in Berkeley, Calif., where notification of an event occurs in as few as 10 seconds. He said a statewide early warning system could give residents up to 90 seconds of warning and when combined with a public education campaign could save lives and reduce damage.
On Monday, crews began the bulk of damage assessments, with door-to-door building checks and going into red tag and yellow tag (first and second priority, respectively) buildings. This will continue for several days. The city of Napa found more than a dozen new red tags on Monday, according to Alexander.
This article was updated on Aug. 25 to include information about the response on Monday.