Does Detroit, MI need an earthquake retrofit?

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Detroit in Seismic Design Category B: 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 Detroit sits at the 30th percentile for seismic hazard among 4,875 US cities.

Detroit by the numbers

The raw figures: peak ground acceleration 0.05g, short-period spectral response 0.101g, 1-second spectral response 0.045g. Among 153 Michigan cities in this dataset, Detroit ranks 45 for seismic hazard, the 71th percentile within the state. About 645,705 people live in Detroit, Michigan.

What a retrofit costs in Detroit

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

Earthquake insurance for a Detroit 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 Detroit address.

More on how this number was built

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