SinkholeOdds

Sinkhole risk in San Miguel 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 San Miguel 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 1,341 of San Miguel County's 4,722 square miles on soluble rock, 1,341 of them with the rock at or near the surface. With about 26,428 residents (6 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 278 map points about 4.1 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around San Miguel County

The nearest county rated sinkhole country is Eddy County, NM, about 211 miles south. 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 Permain and Pennsylvanian rocks, undivided (medium-grained mixed clastic), Permain and Pennsylvanian in age, covering about 7% of the county. Next is the Pennsylvanian rocks, undivided at 5%.

5% 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

San Miguel County ranks 6 of 33 in New Mexico for soluble rock at the surface, and sits above 79% of US counties on that measure.