Lake Forest, IL: what USGS's seismic model says
Lake Forest 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, Lake Forest ranks above 32% of the 4,875 cities in this dataset for seismic hazard - the 32th percentile.
How Lake Forest compares
USGS's underlying values for Lake Forest: 0.053g peak ground acceleration, 0.105g at short period, 0.058g at 1 second. Within Illinois alone, Lake Forest ranks 293 of 330 cities by seismic hazard - the 11th percentile in-state. Lake Forest has a population of about 19,642.
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.
Earthquake insurance for a Lake Forest home
A Lake Forest 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 Lake Forest's figures come from
Lake Forest'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 Lake Forest.