Does South Lyon, MI need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, South Lyon is Category B. 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 South Lyon sits at the 29th percentile for seismic hazard among 4,875 US cities.

How South Lyon compares

USGS's underlying values for South Lyon: 0.048g peak ground acceleration, 0.096g at short period, 0.046g at 1 second. Within Michigan alone, South Lyon ranks 64 of 153 cities by seismic hazard - the 59th percentile in-state. South Lyon has a population of about 12,219.

Retrofit economics for South Lyon

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.

What this means for insurance

A South Lyon 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 South Lyon's figures come from

South Lyon'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 South Lyon.