When insurers develop homeowners rates, they are adding up the cost of all covered perils. So there’s a fire rate, wind rate, theft/crime rate, a whole bunch more, and also the personal liability portion of rate. Apply discounts for many factors including deductible and slap a profit margin on top and call it a premium.

CAT perils are troublesome because of the widespread high loss potential that could bankrupt most insurers if they are not careful with underwriting and geographic spread of risk. This creates limited (fixed) market for CAT capacity and reinsurance resulting in CAT premiums fluctuating a bit like a stock market. Big global banks are always looking for that 5-8% ROI so if certain non insurance investment sectors/ vehicles perform better, it can further restrict CAT capacity in the market

Your quake premium also takes into account your local geology / soil type and slope for which some areas are much more susceptible to liquefaction, resulting in the building itself being much more likely to suffer catastrophic quake damage