Carlinville, IL: what USGS's seismic model says

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Carlinville in Seismic Design Category C: 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, Carlinville ranks above 74% of the 4,875 cities in this dataset for seismic hazard - the 74th percentile.

Carlinville by the numbers

USGS's underlying values for Carlinville: 0.145g peak ground acceleration, 0.28g at short period, 0.122g at 1 second. Within Illinois alone, Carlinville ranks 47 of 330 cities by seismic hazard - the 86th percentile in-state. Carlinville has a population of about 5,582.

What a retrofit costs in Carlinville

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 Carlinville 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 Carlinville's figures come from

Carlinville'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 Carlinville.