Herndon's Seismic Design Category, explained

Herndon carries Seismic Design Category B under USGS's ASCE 7-16 model. 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 Herndon sits at the 46th percentile for seismic hazard among 4,875 US cities.

Herndon by the numbers

The raw figures: peak ground acceleration 0.071g, short-period spectral response 0.137g, 1-second spectral response 0.044g. Among 63 Virginia cities in this dataset, Herndon ranks 39 for seismic hazard, the 39th percentile within the state. About 25,180 people live in Herndon, Virginia.

Bracing and bolting: the actual cost

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

More on how this number was built

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