San Bruno's Seismic Design Category, explained

San Bruno clears the point where the standard Seismic Design Category tables stop applying - USGS returns no letter here, only a flag that a site-specific study (ASCE 7-16 §11.4.8) is required. Treat that as more severe than any lettered category, not as missing data. Rank it against the rest of the country and San Bruno sits at the 100th percentile for seismic hazard among 4,875 US cities.

How San Bruno compares

The raw figures: peak ground acceleration 1.025g, short-period spectral response 2.397g, 1-second spectral response 1.004g. Among 429 California cities in this dataset, San Bruno ranks 9 for seismic hazard, the 98th percentile within the state. About 42,035 people live in San Bruno, California.

What a retrofit costs in San Bruno

Because San Bruno is in California, the EBB grant applies if the ZIP code participates and the house qualifies (wood-framed house on a raised (not slab-on-grade) foundation, built before 1980): a $3,000-$7,000 bracing-and-bolting job drops to $0-$4,000 after the $3,000 base grant, or effectively free for income-eligible households getting the full $10,000.

What this means for insurance

Earthquake coverage in California mostly runs through the California Earthquake Authority (CEA), sold only through licensed agents at CEA-participating insurers - there is no direct-to-consumer CEA policy. A general home-insurance quote is the practical starting point for a San Bruno homeowner asking about it.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced San Bruno's numbers. The retrofit cost and grant guide covers every EBB eligibility rule, including the ones this page can't check.