Standard homeowner's insurance policies do not cover earthquake damage or damage resulting from most "proximate causes," such as flooding or theft. If you want earthquake insurance, you must acquire it separately or additionally as an extended policy. However, the law does not require that you insure your home against damage from an earthquake. In fact, most homeowners in San Francisco do not purchase earthquake insurance at all because of the prohibitive expense and high deductibles.

•  What are the pros and cons of earthquake insurance?

If you have accrued a great deal of equity in your home, the obvious benefit of earthquake insurance is that it protects your investment in the event of a catastrophe. You may also be eligible for discounts in your regular homeowner's coverage and exempt from certain surcharges from Freddie Mac. However, bear in mind that your earthquake insurance is of little value if you have not set aside funds for the substantial deductible — which can be anywhere from five to fifteen percent of your home's replacement value. For a $500,000 house — far less than even the average median home price in San Francisco — that's $50,000 at the ten percent rate. Furthermore, earthquake policies might not include demolition costs or provide enough coverage for temporary housing. Be sure to read the fine print for these and other limitations.

Note that various factors, such as the seismic strength, location, age and size of your home will also affect your rates. For example, newly constructed homes must be built according to the latest code, so they will obtain comparatively better rates. In addition, insurers will usually offer lower premiums for older homes that have been retrofitted for seismic resistance.