Sinkhole risk in Hamilton 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: 0%
Buried under cover: 100%

What to do about a house in Hamilton County

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

That works out to roughly 392 of Hamilton County's 394 square miles on soluble rock. With about 379,704 residents (963 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 393 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Hamilton County

The nearest county rated sinkhole country is Monroe County, IN, about 67 miles southwest. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Madison County, IN 18 mi northeast · 0% at surface
Tipton County, IN 18 mi north · 0% at surface
Marion County, IN 20 mi south · 0% at surface
Hancock County, IN 21 mi southeast · 0% at surface
Boone County, IN 24 mi west · 0% at surface
Clinton County, IN 30 mi northwest · 0% at surface

What Hamilton County is built on

The largest mapped soluble unit here is the Wabash Formation (limestone), Silurian in age, covering about 84% of the county. Next is the Muscatatuck Group at 11%.

Against the rest of Indiana

Hamilton County ranks 52 of 92 in Indiana for soluble rock at the surface, and sits above 0% of US counties on that measure.