Tarrant's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Tarrant is Category C. Moderate seismic hazard. Code adds irregular-building restrictions and requires bracing of some nonstructural components (e.g. tall shelving, water heaters) in addition to structural detailing. Rank it against the rest of the country and Tarrant sits at the 76th percentile for seismic hazard among 4,875 US cities.

Tarrant by the numbers

The raw figures: peak ground acceleration 0.171g, short-period spectral response 0.294g, 1-second spectral response 0.102g. Among 107 Alabama cities in this dataset, Tarrant ranks 24 for seismic hazard, the 78th percentile within the state. About 5,806 people live in Tarrant, Alabama.

What a retrofit costs in Tarrant

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

More on how this number was built

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