Oak Brook's Seismic Design Category, explained

Oak Brook carries Seismic Design Category B under USGS's ASCE 7-16 model. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Oak Brook ranks above 41% of the 4,875 cities in this dataset for seismic hazard - the 41th percentile.

Oak Brook by the numbers

USGS's underlying values for Oak Brook: 0.065g peak ground acceleration, 0.127g at short period, 0.065g at 1 second. Within Illinois alone, Oak Brook ranks 141 of 330 cities by seismic hazard - the 57th percentile in-state. Oak Brook has a population of about 8,188.

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 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 Oak Brook 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 Oak Brook's figures come from

Oak Brook'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 Oak Brook.