Bloomington's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Bloomington is Category B. 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 Bloomington sits at the 45th percentile for seismic hazard among 4,875 US cities.

Where Bloomington sits in Illinois

The raw figures: peak ground acceleration 0.07g, short-period spectral response 0.147g, 1-second spectral response 0.082g. Among 330 Illinois cities in this dataset, Bloomington ranks 90 for seismic hazard, the 73th percentile within the state. About 79,232 people live in Bloomington, Illinois.

What a retrofit costs in Bloomington

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

Insuring against this, not just retrofitting

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 Bloomington address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Bloomington'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.