Sinkhole risk in Miami County, OH: Pockets of it

Pockets of it

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

On soluble rock: 100%
At or near the surface: 0%
Buried under cover: 100%

The next step for one property

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

That works out to roughly 407 of Miami County's 407 square miles on soluble rock. With about 111,950 residents (275 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 355 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 100% under cover still counts, and the signs to look for and how an inspection works.

Counties around Miami County

The nearest county rated sinkhole country is Kenton County, KY, about 79 miles south. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Shelby County, OH 20 mi north · 0% at surface
Montgomery County, OH 21 mi south · 0% at surface
Darke County, OH 21 mi west · 0% at surface
Champaign County, OH 25 mi east · 0% at surface
Clark County, OH 25 mi east · 0% at surface
Greene County, OH 31 mi southeast · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Cincinnati Group as used by Wickstrom (1990) (shale), Ordovician in age, covering about 35% of the county. Next is the Lockport Dolomite at 32%.

Against the rest of Ohio

Miami County ranks 56 of 88 in Ohio for soluble rock at the surface, and sits above 0% of US counties on that measure.