I was curious about this insurance too. I played around with different zip codes and homes courtesy of Redfin and the <a href="http://www.earthquakeauthority.com/index.aspx?id=33">California Earthquake Authority?s</a> website for numbers.
I used a replacement cost of $150/sq ft and 2500 sq ft as a datum, or $375k remembering that the land value presumably remains unchanged.
I selected a 10% deductible, or $37,500 and > one story. Left defaults on the other options.
For:
> Irvine, age 1977, zip 92603, Turtlerock, annual premium = $338
> Irvine, age 2005, zip 92620, Woodbury, annual premium = $953
> Northridge, age 1961, zip 91325, annual premium = $2261
> Anaheim Hills, age 1973, zip 92807, annual premium = $533
> Anaheim Hills (SW portion), age 1974, zip 92867, annual premium = $1519
> Corona Del Mar, age 1986, zip 92625, annual premium = $1208
> Newport Coast, age 1996, zip 92657, annual premium = $338
The risks and geology are complicated on a micro scale. For someone not familiar with the area, it may behoove one to consult a professional, or really spend the time to learn where the riskier areas are.
On another note, earthquake insurance is not as expensive as I originally thought it would be. Going from a 10% to 15% deductible reduces the premium on average about 35%.