Union's Seismic Design Category, explained

Union carries Seismic Design Category C under USGS's ASCE 7-16 model. 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 Union sits at the 75th percentile for seismic hazard among 4,875 US cities.

How Union compares

The raw figures: peak ground acceleration 0.156g, short-period spectral response 0.28g, 1-second spectral response 0.094g. Among 66 South Carolina cities in this dataset, Union ranks 53 for seismic hazard, the 20th percentile within the state. About 7,988 people live in Union, South Carolina.

Retrofit economics for Union

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

Earthquake insurance for a Union home

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 Union address.

More on how this number was built

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