SinkholeOdds

Sinkhole risk in Pinellas 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
65%
At or near the surface
35%
Buried under cover
31%

What to do about a house in Pinellas 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 179 of Pinellas County's 274 square miles on soluble rock, 95 of them with the rock at or near the surface. With about 965,870 residents (3,528 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 242 map points about 1.1 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 Pinellas County

The nearest county rated sinkhole country is Sarasota County, FL, about 52 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Which formation it is

The largest mapped soluble unit here is the Hawthorn Group, Arcadia Formation, Tampa Member (limestone), Eocene in age, covering about 22% of the county. Next is the Hawthorn Group, Arcadia Formation, Tampa Member at 18%.

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

Pinellas County ranks 40 of 67 in Florida for soluble rock at the surface, and sits above 81% of US counties on that measure.