Does Gloucester City, NJ need an earthquake retrofit?

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Gloucester City in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Gloucester City ranks above 55% of the 4,875 cities in this dataset for seismic hazard - the 55th percentile.

Gloucester City by the numbers

The raw figures: peak ground acceleration 0.098g, short-period spectral response 0.177g, 1-second spectral response 0.047g. Among 194 New Jersey cities in this dataset, Gloucester City ranks 160 for seismic hazard, the 18th percentile within the state. About 11,618 people live in Gloucester City, New Jersey.

Bracing and bolting: the actual cost

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for New Jersey. 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 Gloucester City address.

More on how this number was built

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