Berwyn's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Berwyn 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 Berwyn sits at the 38th percentile for seismic hazard among 4,875 US cities.

Where Berwyn sits in Illinois

USGS's underlying values for Berwyn: 0.061g peak ground acceleration, 0.122g at short period, 0.064g at 1 second. Within Illinois alone, Berwyn ranks 219 of 330 cities by seismic hazard - the 34th percentile in-state. Berwyn has a population of about 55,152.

What a retrofit costs in Berwyn

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 Illinois 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 Illinois.

Insuring against this, not just retrofitting

A Berwyn 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 Berwyn's figures come from

Berwyn'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 Berwyn.