Keokuk's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Keokuk is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Keokuk in the 31th percentile nationally for seismic hazard - higher than 31% of the 4,875 US cities USGS was checked against here.

Where Keokuk sits in Iowa

USGS's underlying values for Keokuk: 0.052g peak ground acceleration, 0.11g at short period, 0.073g at 1 second. Within Iowa alone, Keokuk ranks 1 of 85 cities by seismic hazard - the 100th percentile in-state. Keokuk has a population of about 9,462.

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 Iowa 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 Iowa.

What this means for insurance

A Keokuk 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 Keokuk's figures come from

Keokuk'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 Keokuk.