Does Florence, SC need an earthquake retrofit?

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Florence in Seismic Design Category C: Moderate seismic hazard. Code adds irregular-building restrictions and requires bracing of some nonstructural components (e.g. tall shelving, water heaters) in addition to structural detailing. That puts Florence in the 76th percentile nationally for seismic hazard - higher than 76% of the 4,875 US cities USGS was checked against here.

Where Florence sits in South Carolina

USGS's underlying values for Florence: 0.174g peak ground acceleration, 0.319g at short period, 0.115g at 1 second. Within South Carolina alone, Florence ranks 37 of 66 cities by seismic hazard - the 45th percentile in-state. Florence has a population of about 40,923.

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 South Carolina 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 South Carolina.

Earthquake insurance for a Florence home

A Florence 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 Florence's figures come from

Florence's Category C 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 C does and doesn't tell you about Florence.