Somerville's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Somerville in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Somerville in the 63th percentile nationally for seismic hazard - higher than 63% of the 4,875 US cities USGS was checked against here.

Where Somerville sits in Massachusetts

USGS's underlying values for Somerville: 0.167g peak ground acceleration, 0.278g at short period, 0.066g at 1 second. Within Massachusetts alone, Somerville ranks 19 of 58 cities by seismic hazard - the 68th percentile in-state. Somerville has a population of about 82,149.

Bracing and bolting: the actual cost

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.

Earthquake insurance for a Somerville home

A Somerville 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 Somerville's figures come from

Somerville'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 Somerville.