Cal. Ins. Code § 10089.40

(a) Rates established by the authority shall be actuarially sound so as to not be excessive, inadequate, or unfairly discriminatory. Rates shall be established based on the best available scientific information for assessing the risk of earthquake frequency, severity, and loss. Rates shall be equivalent for equivalent risks. Factors the board shall consider in adopting rates include, but are not limited to, the following:
1. (1) Location of the insured property and its proximity to earthquake faults and to other geological factors that affect the risk of earthquake or damage from earthquake.
2. (2) The soil type on which the insured dwelling is built.
3. (3) Construction type and features of the insured dwelling.
4. (4) Age of the insured dwelling.
5. (5) The presence of earthquake hazard reduction factors, including those set forth in subdivision (a) of Section 10089.2.
(b)
1. (1) If scientific information from geologists, seismologists, or similar experts that assesses the frequency or severity of risk of earthquake is considered in setting rates or in arriving at the modeling assumptions upon which those rates are based, the information may be used to establish differentials among risks only if the information, assumptions, and methodology used are consistent with the available geophysical data and the state of the art of scientific knowledge within the scientific community.
2. (2) Scientific information from geologists, seismologists, or similar experts shall not be conclusive to support the establishment of different rates between the most populous rating territories in the northern and southern regions of the state unless that information, as analyzed by experts such as the United States Geological Survey, the California Division of Mines and Geology, and experts in the scientific or academic community, clearly shows a higher risk of earthquake frequency, severity, or loss between those most populous rating territories to support those differences.
3. (3) It is not the intent of the Legislature in adopting this subdivision to mandate a uniform statewide flat rate for California Earthquake Authority policies.
(c) The classification system established by the board shall not be adjusted or tempered in any way to provide rates lower than are justified for classifications that present a high risk of loss or higher than are justified for classifications that present a low risk of loss.
(d) Policyholders who have retrofitted their homes to withstand earthquake shake damage according to standards and to the extent set by the board shall enjoy a premium discount or credit of 5 percent on the authority-issued policy of residential earthquake coverage. For residential dwellings, the 5-percent discount shall be applicable if the dwelling, at a minimum, meets the following requirements: the dwelling was built prior to 1979, is tied to the foundation, has cripple walls braced with plywood or its equivalent, and the water heater is secured to the building frame. For mobilehomes, the 5-percent discount shall be applicable if the mobilehome, at a minimum, is reinforced by an earthquake resistant bracing system certified by the Department of Housing and Community Development. The board may approve a premium discount or credit above 5 percent, as long as the discount or credit is determined actuarially sound by the authority.
(e) All rates shall be approved by the commissioner prior to their use.