SinkholeOdds

Is my property in sinkhole country?

Type your county. You get how much of it sits on limestone, gypsum or salt that can dissolve into sinkholes, how close to the surface that rock is, and what to check next. It comes from the USGS national karst map, so it can tell you whether to look harder at a house, not whether one lot is safe.

3,109 counties in the lower 48. County level: it says whether to look closer, not what is under one lot.
The five answers you can get, read like a borehole: safest ground at the top.
  1. No soluble rock mapped 1,098 counties Harris County, TX
  2. Not karst, but voids possible 108 counties Maricopa County, AZ
  3. Mostly deep or small 869 counties Los Angeles County, CA
  4. Pockets of it 648 counties Dallas County, TX
  5. Sinkhole country 386 counties Miami-Dade County, FL

Share of each county on soluble rock, from the USGS Karst Map of the United States (Weary and Doctor, 2014).

Then check the one property

  1. Your state geological survey's sinkhole map. Florida, Tennessee, Kentucky, Pennsylvania and Missouri all publish reported sinkholes by location. A cluster on the same street is the signal.
  2. The county property appraiser. Past sinkhole claims and repairs often show in the parcel record.
  3. A geotechnical inspection, if either of those turns something up or the house has new cracks, sticking doors or a low spot in the yard. A home inspector cannot see below the slab.
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