Does Henderson, NC need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Henderson is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Henderson in the 33th percentile nationally for seismic hazard - higher than 33% of the 4,875 US cities USGS was checked against here.

How Henderson compares

The raw figures: peak ground acceleration 0.055g, short-period spectral response 0.114g, 1-second spectral response 0.055g. Among 147 North Carolina cities in this dataset, Henderson ranks 121 for seismic hazard, the 18th percentile within the state. About 14,807 people live in Henderson, North Carolina.

What a retrofit costs in Henderson

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

Insuring against this, not just retrofitting

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 Henderson address.

More on how this number was built

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