Does Centralia, IL need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Centralia is Category D. High seismic hazard - this is the category most of coastal California, the Pacific Northwest, and other active fault regions fall into. Code mandates significant seismic detailing and restricts irregular structural configurations. This is the category the Brace + Bolt scope (cripple-wall bracing, foundation bolting) is built for. That puts Centralia in the 86th percentile nationally for seismic hazard - higher than 86% of the 4,875 US cities USGS was checked against here.

Centralia by the numbers

USGS's underlying values for Centralia: 0.347g peak ground acceleration, 0.573g at short period, 0.185g at 1 second. Within Illinois alone, Centralia ranks 13 of 330 cities by seismic hazard - the 96th percentile in-state. Centralia has a population of about 11,787.

Retrofit economics for Centralia

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 Centralia 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 Centralia's figures come from

Centralia's Category D 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 D does and doesn't tell you about Centralia.