Does Madison, NJ need an earthquake retrofit?

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Madison in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Madison in the 63th percentile nationally for seismic hazard - higher than 63% of the 4,875 US cities USGS was checked against here.

Where Madison sits in New Jersey

The raw figures: peak ground acceleration 0.165g, short-period spectral response 0.271g, 1-second spectral response 0.058g. Among 194 New Jersey cities in this dataset, Madison ranks 95 for seismic hazard, the 51th percentile within the state. About 16,555 people live in Madison, New Jersey.

What a retrofit costs in Madison

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 Madison address.

More on how this number was built

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