Romulus's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Romulus is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Romulus in the 32th percentile nationally for seismic hazard - higher than 32% of the 4,875 US cities USGS was checked against here.

Romulus by the numbers

The raw figures: peak ground acceleration 0.054g, short-period spectral response 0.107g, 1-second spectral response 0.047g. Among 153 Michigan cities in this dataset, Romulus ranks 27 for seismic hazard, the 83th percentile within the state. About 24,652 people live in Romulus, Michigan.

Retrofit economics for Romulus

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.

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 Romulus address.

More on how this number was built

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