The devastation in Napa serves as a big reminder many San Diegans aren't ready for "The Big One."
Because strong quakes don't happen very often, seismologists say Southern Californians are lulled into a false sense of security to the point that 90 percent of homes in the state don't have earthquake insurance.
In Napa, some parts of buildings collapsed and others burned to the ground after an unexpected 6.0 magnitude earthquake struck wine country.
"You can have structural damage to a house. You could have damage to the water systems or the gas mains, things like that," says Scripps Institution of Oceanography Seismologist Frank Vernon.
It's problem that earthquake disaster experts say not many Californians are prepared for.
"We insure close to one million homes, and that's the good news,” says California Earthquake Authority CEO Glenn Pomeroy. “But the bad news is that 90 percent of the state homes in California are without any form of protection "
In fact, the California Earthquake Authority says only about 16 percent of San Diego homeowners are covered.
“California is Earthquake Country, and earthquakes happen. They happen without warning. They happen when we least expect them, and they're going to happen again. That is a matter of scientific fact. And it's just important that we take steps to be prepared," says Pomeroy.
Vernon says the San Andreas Fault and the San Jacinto Fault have the potential to cause a stronger magnitude quake than the one in Napa Valley.
"The two biggest hazards for San Diego County are the San Andreas out here, which could go into a high magnitude 7,” says Vernon. “The San Jacinto, which is closer, could go to about a 7 and a half. "
"We don't know when the big one is going to occur,” he says. “We know they will occur, but we don't know when."
The San Diego Red Cross says only about 7 percent of people across the region are prepared for a disaster. To learn how you can get earthquake insurance, click here.