Williamston's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Williamston 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 Williamston sits at the 22th percentile for seismic hazard among 4,875 US cities.

Where Williamston sits in North Carolina

USGS's underlying values for Williamston: 0.042g peak ground acceleration, 0.09g at short period, 0.045g at 1 second. Within North Carolina alone, Williamston ranks 145 of 147 cities by seismic hazard - the 1th percentile in-state. Williamston has a population of about 5,066.

Retrofit economics for Williamston

A full earthquake retrofit typically runs $5,000-$10,000 nationally (around $7,000 typical), driven mainly by house size and foundation type, not by North Carolina specifically. California's Earthquake Brace + Bolt grant, which covers a large share of this cost, is a California-only program and does not apply in North Carolina.

Insuring against this, not just retrofitting

A Williamston homeowner cannot buy a standalone earthquake policy in most cases - it is added to an existing homeowners policy as an endorsement, so the place to start is a regular home-insurance quote.

Where Williamston's figures come from

Williamston's Category B and every number above trace to USGS's own ASCE 7-16 Design Maps service - see the methodology guide. See the category explainer for what Category B does and doesn't tell you about Williamston.