Earthquake insurance doesn't cover water damage from outside your home, such as sewer or drain backup, floods, or tsunamis. For example, if you live near a lake that floods your home after an earthquake, earthquake insurance won't pay to repair the damage. A flood insurance policy will cover it. You must purchase your CEA policy from the same insurance company with which you have your residential policy; see the list of insurers participating in the CEA here.
If your insurance company refuses to open a claim, call the California Department of Insurance immediately. If you have home insurance in California, your company must offer you earthquake insurance. You cannot buy earthquake insurance directly from the CEA, but you buy it directly from insurance companies that are members of the CEA. Your insurance company must offer you earthquake insurance even if your property doesn't meet the current Building Code and Health and Safety Code regulations on screwing foundations and anchoring water heaters.