Steilacoom's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Steilacoom in Seismic Design Category D: 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 Steilacoom in the 90th percentile nationally for seismic hazard - higher than 90% of the 4,875 US cities USGS was checked against here.

Steilacoom by the numbers

USGS's underlying values for Steilacoom: 0.504g peak ground acceleration, 1.376g at short period, 0.482g at 1 second. Within Washington alone, Steilacoom ranks 55 of 125 cities by seismic hazard - the 56th percentile in-state. Steilacoom has a population of about 6,649.

What a retrofit costs in Steilacoom

A full earthquake retrofit typically runs $5,000-$10,000 nationally (around $7,000 typical), driven mainly by house size and foundation type, not by Washington specifically. California's Earthquake Brace + Bolt grant, which covers a large share of this cost, is a California-only program and does not apply in Washington.

What this means for insurance

A Steilacoom homeowner cannot buy a standalone earthquake policy in most cases - it is added to an existing homeowners policy as an endorsement, so the place to start is a regular home-insurance quote.

Where Steilacoom's figures come from

Steilacoom's Category D and every number above trace to USGS's own ASCE 7-16 Design Maps service - see the methodology guide. See the category explainer for what Category D does and doesn't tell you about Steilacoom.