An earthquake is described as "shaking or trembling of the crust of the earth, caused by underground volcanic forces or by breaking and shifting of rock beneath the surface."

Commercial earthquake insurance coverage is usually excluded from the standard policy covering buildings, contents or loss of income. Nonetheless, earthquake coverage can be bought to protect these items, but is relatively costly and usually has a large deductible.

Rates vary from street to street and depend largely on the vicinity and magnitude of the closest fault lines and also on the type of construction used to build the structure.