Sinkhole risk in Coconino County, AZ: Pockets of it

Pockets of it

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

On soluble rock: 56%
At or near the surface: 56%
Buried under cover: 0%

What to do about a house in Coconino 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 10,425 of Coconino County's 18,616 square miles on soluble rock, 10,425 of them with the rock at or near the surface. With about 145,161 residents (8 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 268 map points about 8.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Coconino County

The nearest county rated sinkhole country is Emery County, UT, about 227 miles north. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Navajo County, AZ 87 mi east · 25% at surface
Yavapai County, AZ 94 mi southwest · 12% at surface
Kane County, UT 100 mi north · 15% at surface
Mohave County, AZ 111 mi west · 32% at surface
Apache County, AZ 132 mi east · 10% at surface
Washington County, UT 137 mi northwest · 16% at surface

The rock underneath

The largest mapped soluble unit here is the Permian sedimentary rocks (limestone), Permian in age, covering about 38% of the county. Next is the Permian to Pennsylvanian sedimentary rocks at 7%.

16% 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 Arizona

Coconino County ranks 1 of 15 in Arizona for soluble rock at the surface, and sits above 89% of US counties on that measure.