Brockton's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Brockton in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Brockton ranks above 60% of the 4,875 cities in this dataset for seismic hazard - the 60th percentile.

How Brockton compares

USGS's underlying values for Brockton: 0.124g peak ground acceleration, 0.22g at short period, 0.059g at 1 second. Within Massachusetts alone, Brockton ranks 35 of 58 cities by seismic hazard - the 40th percentile in-state. Brockton has a population of about 105,788.

What a retrofit costs in Brockton

A full earthquake retrofit typically runs $5,000-$10,000 nationally (around $7,000 typical), driven mainly by house size and foundation type, not by Massachusetts specifically. California's Earthquake Brace + Bolt grant, which covers a large share of this cost, is a California-only program and does not apply in Massachusetts.

What this means for insurance

A Brockton homeowner cannot buy a standalone earthquake policy in most cases - it is added to an existing homeowners policy as an endorsement, so the place to start is a regular home-insurance quote.

Where Brockton's figures come from

Brockton's Category B and every number above trace to USGS's own ASCE 7-16 Design Maps service - see the methodology guide. See the category explainer for what Category B does and doesn't tell you about Brockton.