Castle Rock, CO: what USGS's seismic model says

Castle Rock 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. Rank it against the rest of the country and Castle Rock sits at the 59th percentile for seismic hazard among 4,875 US cities.

Castle Rock by the numbers

USGS's underlying values for Castle Rock: 0.119g peak ground acceleration, 0.214g at short period, 0.058g at 1 second. Within Colorado alone, Castle Rock ranks 31 of 79 cities by seismic hazard - the 62th percentile in-state. Castle Rock has a population of about 83,213.

What a retrofit costs in Castle Rock

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 Colorado 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 Colorado.

Insuring against this, not just retrofitting

A Castle Rock 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 Castle Rock's figures come from

Castle Rock'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 Castle Rock.