SinkholeOdds

Sinkhole risk in Sevier County, UT: 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
6%
At or near the surface
6%
Buried under cover
0%

What to do about a house in Sevier County

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

That works out to roughly 109 of Sevier County's 1,910 square miles on soluble rock, 109 of them with the rock at or near the surface. With about 22,520 residents (12 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 314 map points about 2.5 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 Sevier County

The nearest county rated sinkhole country is Emery County, UT, about 61 miles east. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

The largest mapped soluble unit here is the Tertiary (1) sedimentary rocks in southeastern Utah (limestone), Late Paleocene to Early Eocene in age, covering about 3% of the county. Next is the Jurassic (1) sedimentary rocks in central Utah at 2%.

3% 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 Sevire Valley, 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

Sevier County ranks 22 of 29 in Utah for soluble rock at the surface, and sits above 64% of US counties on that measure.