The Napa Valley area is under a state of emergency following a magnitude 6.0 earthquake that struck between Napa and American Canyon at 3:20 a.m. today. This was the largest earthquake in the Bay Area since the magnitude 6.9 Loma Prieta earthquake in 1989, almost 25 years ago.
The 6.0 magnitude quake was followed by a 3.6 magnitude aftershock at 5:47 a.m.
The earthquakes and resulting damage prompted Gov. Jerry Brown to declare a state of emergency for Napa, Solano and Sonoma counties.
"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."
Three major injuries have been reported and 87 people treated at Queen of the Valley Hospital as of 11 a.m. today, according to the City of Napa.
The earthquakes caused some major structural damage in the area including four mobile homes destroyed and three residential fires. The Napa County Fire Department has responded to dozens earthquake related incidents and has received 10 additional CAL FIRE engines to assist with earthquake and aftershock related calls.
Three historic buildings were also damaged, along with other downtown Napa properties.
The City of Napa is also reporting approximately 60 water main leaks, but both the city's water treatment plants are running and water remains safe to drink. However, some residents are without access to water due to main breaks and no or low pressure.
PG&E has reported that 29,000 customers have experienced power outages in Napa County and crews are responding to approximately 50 reported gas leaks.
College student Eduardo Rivera, 20, told the Associated Press that the home he shares with six relatives shook so violently that he kept getting knocked back into his bed as he tried to flee.
"When I woke up, my mom was screaming, and the sound from the earthquake was greater than my mom's screams," Rivera said.
Napa Valley residents and visitors are encouraged to stay off the roads and utilize phones for emergency purposes only. Use of 911 and local emergency rooms should be restricted to life threatening emergencies only. The American Red Cross has set up a shelter at the Crosswalk Community Church in downtown Napa.
The earthquake happened within a 70-km-wide (44 miles) set of major faults of the San Andreas Fault system that forms the boundary between the Pacific and North American tectonic plates near the north shore of San Pablo Bay. The bayshore areas in the San Francisco Bay region are underlain by landfill and bay mud and have experienced disproportionately greater damage during historic earthquakes. Such damage is caused by soil failure in the fills and amplification of ground shaking by the soft bay mud.
At this time, the United States Geological Survey is estimating the probability of a strong and possibly damaging aftershock — magnitude 5 and larger — in the next 7 days at approximately 45 percent. In addition, approximately 25 to 60 small aftershocks — magnitude 3 to 5 — are expected in the same 7-day period and may be felt locally.