Sinkhole risk in Maricopa County, AZ: Not karst, but voids possible

Not karst, but voids possible

No soluble bedrock; some pseudokarst (piping or lava-tube ground).

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

The next step for one property

Not true karst, but soil piping or lava tubes can still open voids - mention it to an inspector.

Across 9,202 square miles, under one square mile of Maricopa County maps onto soluble rock. With about 4,673,096 residents (508 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 266 map points about 5.9 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how ground with no limestone still opens up.

Counties around Maricopa County

The nearest county rated sinkhole country is Emery County, UT, about 404 miles north. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Pinal County, AZ 72 mi southeast · 3% at surface
Yavapai County, AZ 89 mi north · 12% at surface
Yuma County, AZ 91 mi southwest · 0% at surface
La Paz County, AZ 93 mi west · 0% at surface
Pima County, AZ 94 mi southeast · under 1% at surface
Gila County, AZ 102 mi east · 35% at surface

Against the rest of Arizona

Maricopa County ranks 14 of 15 in Arizona for soluble rock at the surface, and sits above 0% of US counties on that measure.