Sinkhole risk in Torrance County, NM: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 28%
At or near the surface: 28%
Buried under cover: 0%

What to do about a house in Torrance County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 937 of Torrance County's 3,345 square miles on soluble rock, 937 of them with the rock at or near the surface. With about 15,986 residents (5 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 371 map points about 3.0 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 Torrance County

The nearest county rated sinkhole country is Eddy County, NM, about 171 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Valencia County, NM 53 mi west · 13% at surface
Bernalillo County, NM 56 mi northwest · 6% at surface
Lincoln County, NM 62 mi southeast · 65% at surface
Santa Fe County, NM 66 mi north · 18% at surface
Guadalupe County, NM 66 mi east · 14% at surface
Socorro County, NM 71 mi southwest · 23% at surface

What Torrance County is built on

The largest mapped soluble unit here is the Yesa Formation (sandstone), Permian in age, covering about 14% of the county. Next is the San Andres Formation at 12%.

14% 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 Permian Basin, Anadarko Basin,Dalhart Basin, Palo Duro 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 Mexico

Torrance County ranks 7 of 33 in New Mexico for soluble rock at the surface, and sits above 78% of US counties on that measure.