SinkholeOdds

Sinkhole risk in Monroe County, FL: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock
55%
At or near the surface
25%
Buried under cover
31%

What to do about a house in Monroe County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

Standard Florida homeowners policies cover only catastrophic ground cover collapse; full sinkhole coverage is a separately priced option insurers must offer.

That works out to roughly 543 of Monroe County's 983 square miles on soluble rock, 243 of them with the rock at or near the surface. With about 80,908 residents (82 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 429 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: what Florida insurers have to cover, and why gypsum and salt move faster than limestone.

Counties around Monroe County

The nearest county rated sinkhole country is Miami-Dade County, FL, about 32 miles east, close enough that the same rock may run under the county line. None of the 6 closest counties land in the same band, so Monroe County stands out from its surroundings.

Which formation it is

The largest mapped soluble unit here is the Tamiami Formation (beach sand), Holocene in age, covering about 20% of the county. Next is the Tamiami Formation at 11%.

The county also lies over the Floridan shelf, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Florida

Monroe County ranks 46 of 67 in Florida for soluble rock at the surface, and sits above 77% of US counties on that measure.