Sinkhole risk in Mercer County, PA: 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: 10%
At or near the surface: 0%
Buried under cover: 10%

The next step for one property

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

That works out to roughly 68 of Mercer County's 673 square miles on soluble rock. With about 108,140 residents (161 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 356 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and why the 10% under cover still counts.

Counties around Mercer County

The nearest county rated sinkhole country is Union County, PA, about 168 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Lawrence County, PA 22 mi south · 6% at surface
Venango County, PA 26 mi east · 5% at surface
Trumbull County, OH 27 mi west · 0% at surface
Crawford County, PA 28 mi north · 0% at surface
Butler County, PA 32 mi southeast · 35% at surface
Mahoning County, OH 34 mi southwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Allegheny Formation (sandstone), Pennsylvanian in age, covering about 10% of the county.

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 Pennsylvania

Mercer County ranks 58 of 67 in Pennsylvania for soluble rock at the surface, and sits above 0% of US counties on that measure.