In 2014, 11 percent of U.S. homeowners with annual incomes of $100,000 or more said they had earthquake insurance, compared with 18 percent last year, according to a recent Insurance Information Institute survey.
Meanwhile, only 2 percent of homeowners with annual incomes less than $35,000 had coverage, down from 6 percent in the year-earlier period, the survey said.
Established by the California legislature in 1996, the CEA collects about $570 million in premiums each year, but it has only paid out $3.6 million in losses since its inception, according to the Insurance Information Institute.
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In 2013, the CEA had more than 841,000 polices in force with an average premium of about $676, the California Department of Insurance said.
Earthquake policy deductibles can range anywhere from 2 percent to 20 percent of a properties replacement value and insurers in high risk states usually set minimum deductibles of about 10 percent, according to Insurance Information Institute research.
Official cost estimates from Sunday's quake are not available, but the U.S. Geological Survey said losses are likely to total more than $1 billion.
"It's still too early to know how much damage has occurred to homes in the affected area," the CEA's CEO, Glenn Pomeroy, said. "We'll have more information available to us during the next few days."
In July 2014 the USGS updated its U.S. national seismic hazard maps for the first time since 2008.
According to the updated maps, 42 states are at risk of earthquakes, with 16 considered at high risk.
—By CNBC's Karma Allen