SinkholeOdds

Sinkhole risk in Tompkins County, NY: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock
under 1%
At or near the surface
0%
Buried under cover
under 1%

The next step for one property

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

That works out to roughly 1 of Tompkins County's 475 square miles on soluble rock. With about 105,602 residents (222 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 353 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Tompkins County

The nearest county rated sinkhole country is Union County, PA, about 107 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Tompkins County is built on

The largest mapped soluble unit here is the Tully Limestone (limestone), Middle Devonian in age, covering about under 1% 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 New York

Tompkins County ranks 55 of 62 in New York for soluble rock at the surface, and sits above 0% of US counties on that measure.