A 6.0 earthquake that centered near South Napa shook Bay Area residents in their beds early Sunday morning. U.S. Geological Survey officials said the earthquake is the largest to hit the Bay Area since the Loma Prieta Earthquake almost 25 years ago.
The temblor was recorded at 3:20 a.m. and was located about four miles northwest of American Canyon and six miles south-southwest of Napa, according to the Menlo Park-based USGS. It struck about seven miles below the earth's surface, USGS. officials said. The earthquake lies within a 44-mile wide set of major faults of the San Andreas Fault system that forms the boundary between the Pacific and North American tectonic plates, according to the USGS. It was reportedly felt as far north as Ukiah to as far south as Salinas. The earthquake moved the earth several inches along the West Napa Fault, the most seismically active fault mapped between the Rogers Creek Fault to the west and the Concord-Gree Valley Fault to the east, according to the USGS.
The USGS. also reported 2.5 and 3.6 magnitude aftershocks about four miles southwest of Napa at 5:01 a.m. and 5:47 a.m., respectively. There were also more than 50 to 60 aftershocks reported throughout Sunday. As of the afternoon, the largest aftershock had a magnitude of 3.6, John Parrish, a geologist with the state Department of Conservation, said at a press conference.
Officials have said 30 to 70 small aftershocks could hit the area during the next week, but none will be as strong as the initial earthquake.
Napa city officials reported Monday morning that a total of 208 patients have been treated at Queen of the Valley Medical Center with 17 admitted. This is up from the 172 patients reported Sunday afternoon.
Most injuries are orthopedic, according to the city, and no new patients have been treated since 11 p.m. on Sunday. There have been no fatalities related to the earthquake.
It was initially reported that three people were critically injured -- two adults and a 13-year-old boy who was airlifted to a children's hospital outside of Napa after pieces of the fireplace at his home collapsed onto him. A hospital official said at a press briefing mid-day on Sunday that the number of critically injured people was raised to six after three patients required orthopedic surgery. Two of them suffered fractured hips and a third, a fractured ankle, the spokesman said. Some patients also suffered from heart attacks, the spokesman said, and many were injured while trying to clean up after the earthquake -- the main reason the number of injuries rose throughout the day.
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.
A city spokesman said firefighters have been responding to structure fires, and a number of masonry buildings in downtown Napa suffered severe damage. As of Monday, 49 residential and commercial buildings have been red-tagged, or deemed uninhabitable, and more than 100 yellow-tagged, meaning people can only enter for limited purposes, city officials said. Napa's senior center, post office and one side of the courthouse have been red-tagged. The number of identified water main breaks rose to 90 on Monday morning, up from about 60 on Sunday. Eight breaks were repaired on Sunday night, according to the city.
Beginning Monday, 20 to 30 Office of Emergency Services building inspectors began work in Napa, and 10 crews will work on water line repairs using regional mutual aid, the city said. All water line repairs can be completed by Wednesday or Thursday at the latest, according to the City of Napa.
City officials announced Sunday afternoon that all Napa Valley Unified School District schools will be closed Monday. However, Sonoma State University -- located about 25 miles from the epicenter of the early morning earthquake -- will be open, as well as Napa City College.
Multiple structures throughout downtown Vallejo and Mare Island were damaged, with city officials estimating $5 million in damages and City Manager Daniel Keen declaring a state of emergency for the city. As of late Monday morning, 41 buildings in Vallejo were reportedly damaged, city officials said. Some roads were closed due to damage.
The earthquake left behind collapsed awnings and facades; broken windows and glass; damaged sprinkler systems and downed chimneys, city officials said. There were also 16 water main breaks and individual water outages.
After about 70,000 people were initially left without power in Sonoma and Napa counties on Sunday, electricity was steadily restored throughout the day and continuing through Monday. As of shortly after 10 a.m., only 10 PG&E customers remained without power. PG&E spokeswoman Nicole Liebelt said crews worked through the night to restore power to customers.
Of 439 gas odor calls PG&E had received Sunday, crews visited approximately 400 of those customers and planned to go to the other 39 sites Sunday evening, Guidi said. Starting Monday, crews will conduct courtesy gas safety checks at homes and businesses affected by the earthquake.
The California Highway Patrol reported around 10:30 a.m. on Sunday that all roads were open and accessible to the general public after being fully inspected. Damage was found at State Route 121 at State Route 29; State ROute 121 at Cuttings Wharf; Old Sonoma Road between Congress Valley Road and Buhman Road; and Petrified Forest Road at Saxton Road.
CHP officials are asking for the public's help in detecting additional damaged roads, particularly damage that could result in a crash. Anyone with information can call 1-800-835-5247.
There has been no reported damage to roadways in the South Bay, Peninsula and East Bay, according to the CHP.
Caltrain experienced delays of up to 50 minutes Sunday as officials inspected the northern portion of the system's tracks before clearing them for operation. ACE cancelled its special 49ers service as a result of the earthquake, but Caltrain provided service to Levi's Stadium in Santa Clara.
VTA service was not impacted but also reported delays on Sunday due to overuse.
Law enforcement and emergency agencies across the Bay Area are asking residents not to call 911 unless they have an emergency.
California Gov. Edmund Brown Jr., who along with the City of Napa declared a state of emergency Sunday morning, said in a statement that the impact of the earthquake is being felt throughout the region.
"My Office of Emergency Services has been on full activation since early this morning and is working close with state and local emergency managers, first responders and transportation officials to respond to impacts to residents and critical infrastructure," he said Sunday. "These safety officials are doing all they can to help residents and those living in affected areas should follow their guidance and instruction."
The governor included power outages to tens of thousands of residents, continued aftershocks and fires as additional reasons for this morning's emergency declaration. The declaration allows all available state resources to be directed toward earthquake response efforts.
Seven geologists from the state Geological Survey have coordinated with USGS. teams from Menlo Park to compile data further data on the earthquake, geologist John Parniss said.
Read this USGS. tectonic summary for more detail about the origin and location of Sunday's earthquake.
Read related content:
• 'Hidden' earthquake faults underlie Peninsula (February 2011)
• 20 years later, experts predict bigger quake (October 2009)
• Loma Prieta earthquake -- 18 years later (October 2007)