Earthquakes and California real estate: The costs are even worse than you imagined

Maybe we should all just move.

A recent earthquake forecast has raised the possibility that a powerful quake could now rupture simultaneously in Northern and Southern California. Were that to happen, guess what? Lots of houses would be damaged or destroyed.

CoreLogic, the real estate information service, has helpfully computed just how many: up to 3.5 million if a north-south earthquake of magnitude 8.3 were to occur. The estimated reconstruction costs could be $289 billion.

Those numbers are significantly higher than in many previous estimates. And why is that? Because earthquake modeling traditionally has held that ruptures would occur either in the north or in the south. For instance, the San Andreas Fault has long been viewed as having independent segments with ruptures on the northern or southern faults deemed mutually exclusive of one another.

That thinking changed last year, when the Uniform California Earthquake Rupture Forecast, Version 3, posited that the big one could be really big, running the length of the state.

And so we return to CoreLogic’s numbers. The statewide projection of 3.5 million damaged homes represents a 126 percent increase over the 1.6 million homes that could be damaged if an 8.3 earthquake struck only in the north – and a 54 percent increase over the 2.3 million homes that could be damaged if a temblor of the same magnitude hit only in the south.

Similarly, the $289 billion in statewide reconstruction costs is 79 percent higher than the $161 billion projected for a northern-only quake and 111 percent higher than the $137 billion forecast for a southern-only quake.

CoreLogic also has projected levels of real estate destruction for statewide earthquakes of magnitudes 8.2 and 8.0. You can see all the numbers here.

Photo: A home in Boulder Creek, CA, that was damaged in the Loma Prieta Earthquake on October 17, 1989 (AP/Douglas C. Pizac)


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  • Look at the Southern San Andreas rupture of 1857, almost 250 miles long. That alone could cause an 8-plus magnitude quake, which would do so much damage to the L.A. basin that more than 15 million people would be trapped without replenishments of food and water. The worst quakes I remember were the 1971 and 1994 quakes, but the people and the deliveries of food and water were not cut off to the wider area. The Big One will be unprecedented, not just in damage, but by the utter hopelessness of getting supplies into the disaster area to serve and protect 15-20 million people.