Sinkhole risk in New Hanover County, NC: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 79%
At or near the surface: 79%
Buried under cover: 0%

The next step for one property

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 151 of New Hanover County's 192 square miles on soluble rock, 151 of them with the rock at or near the surface. With about 243,333 residents (1,266 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 447 map points about 0.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around New Hanover County

The closest county with no soluble rock mapped is Hyde County, NC, about 129 miles northeast. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Pender County, NC 23 mi north · 89% at surface
Brunswick County, NC 23 mi southwest · 30% at surface
Columbus County, NC 45 mi west · 80% at surface
Onslow County, NC 45 mi northeast · 65% at surface
Bladen County, NC 48 mi northwest · 38% at surface
Duplin County, NC 52 mi north · 93% at surface

What New Hanover County is built on

The largest mapped soluble unit here is the Castle Hayne Formation; Comfort Member and New Hanover Member, undivided (limestone), Tertiary in age, covering about 51% of the county. Next is the Peedee Formation at 28%.

Against the rest of North Carolina

New Hanover County ranks 12 of 100 in North Carolina for soluble rock at the surface, and sits above 94% of US counties on that measure.