Ridgefield's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Ridgefield in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Ridgefield in the 66th percentile nationally for seismic hazard - higher than 66% of the 4,875 US cities USGS was checked against here.

How Ridgefield compares

The raw figures: peak ground acceleration 0.183g, short-period spectral response 0.295g, 1-second spectral response 0.061g. Among 194 New Jersey cities in this dataset, Ridgefield ranks 30 for seismic hazard, the 85th percentile within the state. About 11,666 people live in Ridgefield, New Jersey.

What a retrofit costs in Ridgefield

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.

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 Ridgefield address.

More on how this number was built

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