Twin Falls's Seismic Design Category, explained

Twin Falls carries Seismic Design Category B under USGS's ASCE 7-16 model. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Twin Falls in the 52th percentile nationally for seismic hazard - higher than 52% of the 4,875 US cities USGS was checked against here.

Twin Falls by the numbers

USGS's underlying values for Twin Falls: 0.084g peak ground acceleration, 0.191g at short period, 0.082g at 1 second. Within Idaho alone, Twin Falls ranks 35 of 36 cities by seismic hazard - the 3th percentile in-state. Twin Falls has a population of about 55,589.

Retrofit economics for Twin Falls

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 Idaho 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 Idaho.

Insuring against this, not just retrofitting

A Twin Falls 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 Twin Falls's figures come from

Twin Falls's Category B 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 B does and doesn't tell you about Twin Falls.