Sinkhole risk in Comanche County, OK: 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: 13%
At or near the surface: 13%
Buried under cover: 0%

What this means before you buy

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

That works out to roughly 143 of Comanche County's 1,069 square miles on soluble rock, 143 of them with the rock at or near the surface. With about 121,396 residents (114 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 343 map points about 1.8 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 how these percentages are measured.

Counties around Comanche County

The nearest county rated sinkhole country is Caddo County, OK, about 35 miles north, close enough that the same rock may run under the county line. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Cotton County, OK 26 mi south · 0% at surface
Tillman County, OK 33 mi southwest · 0% at surface
Kiowa County, OK 34 mi northwest · 4% at surface
Caddo County, OK 35 mi north · 79% at surface
Stephens County, OK 37 mi east · 9% at surface
Grady County, OK 42 mi northeast · 42% at surface

The rock underneath

The largest mapped soluble unit here is the Rush Springs Formation (sandstone), Early Permian in age, covering about 4% of the county. Next is the El Reno Group at 3%.

11% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Oklahoma

Comanche County ranks 40 of 77 in Oklahoma for soluble rock at the surface, and sits above 70% of US counties on that measure.