Sanibel, FL: what USGS's seismic model says

Sanibel carries Seismic Design Category A under USGS's ASCE 7-16 model. Lowest seismic design category. Building code requires no seismic-specific detailing here beyond ordinary construction practice. Rank it against the rest of the country and Sanibel sits at the 1th percentile for seismic hazard among 4,875 US cities.

Sanibel by the numbers

USGS's underlying values for Sanibel: 0.02g peak ground acceleration, 0.043g at short period, 0.023g at 1 second. Within Florida alone, Sanibel ranks 198 of 228 cities by seismic hazard - the 13th percentile in-state. Sanibel has a population of about 6,358.

What a retrofit costs in Sanibel

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 Florida 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 Florida.

Insuring against this, not just retrofitting

A Sanibel 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 Sanibel's figures come from

Sanibel's Category A 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 A does and doesn't tell you about Sanibel.