Too many Californians are tempting fate, facing financial disaster when the next catastrophic earthquake devastates the state.

They have no insurance that would help them rebuild their homes. Regular homeowner policies don’t cover earthquake damage, and only 10 percent of households in the state carry quake insurance, according to the California Earthquake Authority.

One reason: Earthquake insurance is expensive. A policy covering a $400,000 San Francisco home might cost $1,105 a year on top of regular homeowners insurance.

Another reason: Deductibles are so high — 10 to 15 percent — that many homeowners would receive little money unless their homes sustained major damage.

To help Californians shield themselves from ruin in the event of a major quake, Sen. Dianne Feinstein, D-Calif., has introduced federal legislation designed to make earthquake coverage more affordable.

One factor driving up rates is the expensive reinsurance that insurance companies themselves buy in case they have to pay out millions or billions in claims after a seismic cataclysm. The Earthquake Authority, a nonprofit but state-managed organization that sells 70 percent of the residential earthquake policies in California, spends nearly $200 million a year on reinsurance.

Feinstein’s bill, SB637, would establish federal loan guarantees that would make it easier for the Earthquake Authority to borrow money when and if it needs to cover claims from a major disaster. The idea is to reduce the amount the authority spends on reinsurance — sponsors say the bill would save nearly $500 million in the first five years. That would allow the authority to reduce rates roughly 30 percent and to offer lower deductibles.

Critics of the measure claim it would put U.S. taxpayers at risk. But Feinstein, after conferring with the Congressional Budget Office, told the Senate that the bill would cost taxpayers nothing. The Earthquake Authority says a modest increase in premiums would enable it to repay any federal loans.