Rock Island, IL: what USGS's seismic model says

Rock Island 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. Rank it against the rest of the country and Rock Island sits at the 26th percentile for seismic hazard among 4,875 US cities.

Rock Island by the numbers

USGS's underlying values for Rock Island: 0.045g peak ground acceleration, 0.095g at short period, 0.065g at 1 second. Within Illinois alone, Rock Island ranks 330 of 330 cities by seismic hazard - the 0th percentile in-state. Rock Island has a population of about 36,434.

Retrofit economics for Rock Island

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 Rock Island 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 Rock Island's figures come from

Rock Island'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 Rock Island.