SinkholeOdds

Sinkhole risk in Ingham County, MI: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock
6%
At or near the surface
0%
Buried under cover
6%

What to do about a house in Ingham County

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 33 of Ingham County's 556 square miles on soluble rock. With about 290,427 residents (522 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 386 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and why the 6% under cover still counts.

Counties around Ingham County

The nearest county rated sinkhole country is Genesee County, MI, about 44 miles northeast. 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 Michigan Formation (black shale), Mississippian in age, covering about 3% of the county. Next is the Bayport Limestone at 3%.

3% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

The county also lies over the Michigan Basin; Ohio Basin; Appalachian Basin, 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 Michigan

Ingham County ranks 41 of 83 in Michigan for soluble rock at the surface, and sits above 0% of US counties on that measure.