Duncan, OK: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Duncan 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. Nationally, Duncan ranks above 78% of the 4,875 cities in this dataset for seismic hazard - the 78th percentile.

How Duncan compares

The raw figures: peak ground acceleration 0.22g, short-period spectral response 0.364g, 1-second spectral response 0.096g. Among 75 Oklahoma cities in this dataset, Duncan ranks 9 for seismic hazard, the 89th percentile within the state. About 23,174 people live in Duncan, Oklahoma.

Retrofit economics for Duncan

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

More on how this number was built

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