Does Gloucester, MA need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Gloucester is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Gloucester in the 67th percentile nationally for seismic hazard - higher than 67% of the 4,875 US cities USGS was checked against here.

Where Gloucester sits in Massachusetts

The raw figures: peak ground acceleration 0.19g, short-period spectral response 0.31g, 1-second spectral response 0.07g. Among 58 Massachusetts cities in this dataset, Gloucester ranks 9 for seismic hazard, the 86th percentile within the state. About 30,491 people live in Gloucester, Massachusetts.

What a retrofit costs in Gloucester

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Massachusetts. 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 Gloucester address.

More on how this number was built

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