SinkholeOdds

Sinkhole risk in Emery County, UT: Sinkhole country

Sinkhole country

Fast-dissolving gypsum or salt beds under a large part of the county.

On soluble rock
30%
At or near the surface
30%
Buried under cover
0%

What to do about a house in Emery County

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 1,352 of Emery County's 4,463 square miles on soluble rock, 1,352 of them with the rock at or near the surface. With about 10,161 residents (2 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 297 map points about 3.9 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 the signs to look for and how an inspection works.

Counties around Emery County

The closest county with no soluble rock mapped is Carbon County, UT, about 46 miles north. None of the 6 closest counties land in the same band, so Emery County stands out from its surroundings.

Which formation it is

The largest mapped soluble unit here is the Jurassic (1) sedimentary rocks in southeastern Utah (sandstone), Middle to Late Jurassic in age, covering about 22% of the county. Next is the Jurassic (1) sedimentary rocks in southeastern Utah at 22%.

30% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

The county also lies over the Paradox 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 Utah

Emery County ranks 2 of 29 in Utah for soluble rock at the surface, and sits above 79% of US counties on that measure.