Sinkhole risk in Miami County, IN: 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: 100%
At or near the surface: under 1%
Buried under cover: 99%

What to do about a house in Miami County

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

That works out to roughly 374 of Miami County's 374 square miles on soluble rock, 2 of them with the rock at or near the surface. With about 35,613 residents (95 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 316 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Miami County

The nearest county rated sinkhole country is Monroe County, IN, about 114 miles south. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Wabash County, IN 14 mi east · 0% at surface
Cass County, IN 16 mi west · 4% at surface
Howard County, IN 20 mi south · 0% at surface
Fulton County, IN 22 mi northwest · 0% at surface
Grant County, IN 27 mi southeast · 0% at surface
Huntington County, IN 30 mi east · under 1% at surface

Which formation it is

The largest mapped soluble unit here is the Wabash Formation (limestone), Silurian in age, covering about 98% of the county. Next is the Pleasant Mills Formation at 2%.

Against the rest of Indiana

Miami County ranks 26 of 92 in Indiana for soluble rock at the surface, and sits above 53% of US counties on that measure.