Sinkhole risk in Humboldt County, NV: 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: 8%
At or near the surface: 8%
Buried under cover: 0%

What to do about a house in Humboldt County

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

That works out to roughly 742 of Humboldt County's 9,641 square miles on soluble rock, 742 of them with the rock at or near the surface. With about 17,116 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 311 map points about 5.6 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 Humboldt County

The nearest county rated sinkhole country is Emery County, UT, about 424 miles east. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Pershing County, NV 69 mi south · 16% at surface
Washoe County, NV 93 mi southwest · 2% at surface
Lander County, NV 119 mi southeast · 8% at surface
Harney County, OR 123 mi north · 0% at surface
Malheur County, OR 126 mi north · under 1% at surface
Owyhee County, ID 128 mi northeast · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Shale, mudstone, siltstone, sandstone, and carbonate rock; sparse volcanic rock (claystone), Late Triassic to Early Jurassic in age, covering about 5% of the county. Next is the Tuffaceous sedimentary rocks at 3%.

5% 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 Nevada

Humboldt County ranks 10 of 17 in Nevada for soluble rock at the surface, and sits above 66% of US counties on that measure.