Does Colusa, CA need an earthquake retrofit?

Colusa carries Seismic Design Category D under USGS's ASCE 7-16 model. High seismic hazard - this is the category most of coastal California, the Pacific Northwest, and other active fault regions fall into. Code mandates significant seismic detailing and restricts irregular structural configurations. This is the category the Brace + Bolt scope (cripple-wall bracing, foundation bolting) is built for. That puts Colusa in the 85th percentile nationally for seismic hazard - higher than 85% of the 4,875 US cities USGS was checked against here.

How Colusa compares

The raw figures: peak ground acceleration 0.318g, short-period spectral response 0.738g, 1-second spectral response 0.314g. Among 429 California cities in this dataset, Colusa ranks 371 for seismic hazard, the 14th percentile within the state. About 6,589 people live in Colusa, California.

Retrofit economics for Colusa

Because Colusa 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 Colusa homeowner asking about it.

More on how this number was built

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