Decorah's Seismic Design Category, explained

Decorah 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. Rank it against the rest of the country and Decorah sits at the 16th percentile for seismic hazard among 4,875 US cities.

Decorah by the numbers

USGS's underlying values for Decorah: 0.026g peak ground acceleration, 0.053g at short period, 0.042g at 1 second. Within Iowa alone, Decorah ranks 70 of 85 cities by seismic hazard - the 18th percentile in-state. Decorah has a population of about 7,454.

Retrofit economics for Decorah

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 Iowa 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 Iowa.

What this means for insurance

A Decorah 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 Decorah's figures come from

Decorah'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 Decorah.