Sweetwater's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Sweetwater is Category D. High seismic hazard - this is the category most of coastal California, the Pacific Northwest, and other active fault regions fall into. Code mandates significant seismic detailing and restricts irregular structural configurations. This is the category the Brace + Bolt scope (cripple-wall bracing, foundation bolting) is built for. That puts Sweetwater in the 88th percentile nationally for seismic hazard - higher than 88% of the 4,875 US cities USGS was checked against here.

How Sweetwater compares

The raw figures: peak ground acceleration 0.427g, short-period spectral response 0.63g, 1-second spectral response 0.137g. Among 104 Tennessee cities in this dataset, Sweetwater ranks 26 for seismic hazard, the 76th percentile within the state. About 6,676 people live in Sweetwater, Tennessee.

Retrofit economics for Sweetwater

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

More on how this number was built

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