California authorities are hoping Thursday's earthquake proves to be a wakeup call for residents who may not be ready for the big one.

A majority of California residents live near an active fault line, but only about 10% have purchased earthquake insurance.

Had Thursday's quake occurred under a densely populated area, the state would likely be dealing with "many more injuries and damages in the billions," according to the CEO of the California Earthquake Authority.

With Californians still getting rattled by the aftershocks of Thursday's powerful earthquake, state authorities are hoping the Independence Day trembler will serve as a wakeup call to residents to get ready for the next one. And there will be a next one -- maybe even the big one.

There's a 99% chance that a strong earthquake with a magnitude of 6.7 or greater will hit California in the next 30 years, and a majority of California residents live within 30 miles of an active fault line, according to experts. Yet just 13% of the state's residents purchased earthquake coverage in 2017, according to a July 2018 study by the California Department of Insurance.

That 13% figure, however, involves Californians with homeowner insurance, and is actually smaller when looking at insured and uninsured residents, according to Glenn Pomeroy, CEO of the California Earthquake Authority, or CEA, a nonprofit that offers residential earthquake insurance to Californians.

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"It's alarming to think only about 10% of homes in California have earthquake insurance," Pomeroy said. "California is home to two-thirds of the nation's earthquake risk."

If Thursday's quake had occurred under a densely populated area, it's "likely that California would be looking at many more injuries and damages in the billions of dollars," Pomeroy stated. "This event is an important reminder that all of California is earthquake country. We need to listen to the experts in the field who've been telling us for some time we're going to get hit again, that the pressures on the faults are building."

The CEA, a privately funded but publicly managed organization, has about 2,000 policyholders in the areas affected by this week's quake, according to Pomeroy. It insures more than 1 million households in the state overall.

"People in California don't have to purchase earthquake insurance, generally speaking, when they are buying a home. It's not a requirement like if you're in a flood zone," said Janet Ruiz, a spokesperson for the Insurance Information Institute, a New York-based industry association. Lenders require homeowners to purchase fire insurance when they sign up for a mortgage, but quake coverage is not part of a basic homeowners policy, she said.

"Drop, cover and hold on"

When Californians receive insurance renewals, they include a notification telling them they don't have earthquake insurance on their standard policies, according to Ruiz. "It's something for people to consider. FEMA payouts are not going to cover it," she added of the Federal Emergency Management Agency, the agency created to help respond to domestic disasters.

While the quake safety mantra from officials as to what to do when the ground starts shaking is "drop, cover and hold on," other steps to prepare for surviving and recovering from damaging quakes include retrofitting homes built before 1980 and the advent of more quake-conscious building codes.

"In an earthquake, older homes will shake off their foundation," said Ruiz, who noted that the CEA offers grants to help finance fixes through its "Earthquake Brace and Bolt" program.

The CEA was created by lawmakers after the 1994 Northridge Earthquake killed 57 people and injured more than 9,000. The quake, centered in the San Fernando Valley, sparked fires, landslides and collapsed buildings and freeway overpasses, and snapped water and gas lines. "We were organized by the state of California after a big earthquake 25 years ago caused $40 billion in property damage, and insurance companies didn't want to have anything to do with earthquake insurance anymore," explained the CEA's Pomeroy.

Cost: $800 a year, on average

While the cost of earthquake insurance surged after Northridge, prices have come down more than 50% since CEA was formed, said Pomeroy. "We insure the home for its reconstruction value not its market value," with the rates based on location and when a home was constructed, he explained.

Earthquake insurance cost $800 a year on average, but what might cost $300 in Sacramento could come to two grand in Los Angeles, where the threat is higher, Pomeroy said.

In addition to the CEA, several companies sell earthquake insurance, with one recently introduced product that pays out claims to those living in an impacted area, even if there's no damage. "The trigger is the actual earthquake but you don't have to have damage per se," said Ruiz. "You might have to evacuate, so there can be actual costs even if you don't have damage."

California is not alone in being a quake-prone state. States with quake activity in recent years include Alaska, Hawaii, Idaho, Kansas, Montana, Nevada, Oklahoma and Missouri, Washington and Utah, according to the U.S.Geological Survey.