Blue Island's Seismic Design Category, explained

Blue Island 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 Blue Island sits at the 39th percentile for seismic hazard among 4,875 US cities.

How Blue Island compares

The raw figures: peak ground acceleration 0.062g, short-period spectral response 0.124g, 1-second spectral response 0.066g. Among 330 Illinois cities in this dataset, Blue Island ranks 200 for seismic hazard, the 40th percentile within the state. About 21,805 people live in Blue Island, Illinois.

Retrofit economics for Blue Island

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.

What this means for insurance

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 Blue Island address.

More on how this number was built

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