Spirit Lake, IA: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Spirit Lake is Category A. Lowest seismic design category. Building code requires no seismic-specific detailing here beyond ordinary construction practice. Nationally, Spirit Lake ranks above 9% of the 4,875 cities in this dataset for seismic hazard - the 9th percentile.

Spirit Lake by the numbers

The raw figures: peak ground acceleration 0.028g, short-period spectral response 0.06g, 1-second spectral response 0.037g. Among 85 Iowa cities in this dataset, Spirit Lake ranks 81 for seismic hazard, the 5th percentile within the state. About 5,548 people live in Spirit Lake, Iowa.

Retrofit economics for Spirit Lake

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Iowa. A typical retrofit still runs $5,000-$10,000 nationally, about $7,000 for a common single-family job.

Earthquake insurance for a Spirit Lake home

Outside California, earthquake coverage is typically sold as an endorsement added to a standard homeowners policy, not a separate product - worth asking about directly when getting a home-insurance quote for a Spirit Lake address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Spirit Lake's numbers. The guide to what a Seismic Design Category actually means covers why a category is never a substitute for an engineer's assessment of one specific house.