Holly's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Holly is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Holly ranks above 21% of the 4,875 cities in this dataset for seismic hazard - the 21th percentile.

Where Holly sits in Michigan

USGS's underlying values for Holly: 0.041g peak ground acceleration, 0.085g at short period, 0.043g at 1 second. Within Michigan alone, Holly ranks 109 of 153 cities by seismic hazard - the 29th percentile in-state. Holly has a population of about 5,980.

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 Michigan 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 Michigan.

Earthquake insurance for a Holly home

A Holly 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 Holly's figures come from

Holly'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 Holly.