Does Charleston, IL need an earthquake retrofit?

Charleston 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, Charleston ranks above 73% of the 4,875 cities in this dataset for seismic hazard - the 73th percentile.

How Charleston compares

USGS's underlying values for Charleston: 0.133g peak ground acceleration, 0.258g at short period, 0.114g at 1 second. Within Illinois alone, Charleston ranks 49 of 330 cities by seismic hazard - the 85th percentile in-state. Charleston has a population of about 17,361.

What a retrofit costs in Charleston

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 Charleston home

A Charleston 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 Charleston's figures come from

Charleston'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 Charleston.