Florence's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Florence 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 Florence sits at the 57th percentile for seismic hazard among 4,875 US cities.

How Florence compares

The raw figures: peak ground acceleration 0.102g, short-period spectral response 0.232g, 1-second spectral response 0.075g. Among 57 Arizona cities in this dataset, Florence ranks 32 for seismic hazard, the 45th percentile within the state. About 24,891 people live in Florence, Arizona.

What a retrofit costs in Florence

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Arizona. 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 Florence address.

More on how this number was built

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