Fortuna's Seismic Design Category, explained

Fortuna 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. That puts Fortuna in the 100th percentile nationally for seismic hazard - higher than 100% of the 4,875 US cities USGS was checked against here.

Fortuna by the numbers

The raw figures: peak ground acceleration 0.994g, short-period spectral response 2.123g, 1-second spectral response 1.074g. Among 429 California cities in this dataset, Fortuna ranks 19 for seismic hazard, the 96th percentile within the state. About 12,114 people live in Fortuna, California.

Bracing and bolting: the actual cost

Because Fortuna 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.

Insuring against this, not just retrofitting

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 Fortuna homeowner asking about it.

More on how this number was built

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