Madison's Seismic Design Category, explained

Madison carries Seismic Design Category C under USGS's ASCE 7-16 model. 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. That puts Madison in the 67th percentile nationally for seismic hazard - higher than 67% of the 4,875 US cities USGS was checked against here.

Madison by the numbers

The raw figures: peak ground acceleration 0.072g, short-period spectral response 0.149g, 1-second spectral response 0.087g. Among 61 Mississippi cities in this dataset, Madison ranks 31 for seismic hazard, the 50th percentile within the state. About 28,210 people live in Madison, Mississippi.

Retrofit economics for Madison

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Mississippi. A typical retrofit still runs $5,000-$10,000 nationally, about $7,000 for a common single-family job.

Earthquake insurance for a Madison home

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.