Westchester, IL: what USGS's seismic model says

Under the seismic model IBC and ASCE 7 use for new construction, Westchester is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Westchester ranks above 40% of the 4,875 cities in this dataset for seismic hazard - the 40th percentile.

Westchester by the numbers

USGS's underlying values for Westchester: 0.063g peak ground acceleration, 0.125g at short period, 0.064g at 1 second. Within Illinois alone, Westchester ranks 178 of 330 cities by seismic hazard - the 46th percentile in-state. Westchester has a population of about 16,313.

What a retrofit costs in Westchester

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.

What this means for insurance

A Westchester 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 Westchester's figures come from

Westchester'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 Westchester.