Jacksonville's Seismic Design Category, explained

Jacksonville carries Seismic Design Category C under USGS's ASCE 7-16 model. Moderate seismic hazard. Code adds irregular-building restrictions and requires bracing of some nonstructural components (e.g. tall shelving, water heaters) in addition to structural detailing. Nationally, Jacksonville ranks above 69% of the 4,875 cities in this dataset for seismic hazard - the 69th percentile.

Jacksonville by the numbers

USGS's underlying values for Jacksonville: 0.091g peak ground acceleration, 0.187g at short period, 0.1g at 1 second. Within Illinois alone, Jacksonville ranks 57 of 330 cities by seismic hazard - the 83th percentile in-state. Jacksonville has a population of about 17,801.

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 Jacksonville 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 Jacksonville's figures come from

Jacksonville's Category C 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 C does and doesn't tell you about Jacksonville.