What causes a sudden sinkhole or depression near an Oklahoma house?
In short: A round or sudden depression in the yard or near a house can be a sinkhole over dissolving rock or a washout where flowing water has carried soil away. Parts of Oklahoma, especially the gypsum country of the west and the limestone areas of the northeast and south, have rock that dissolves, and the Oklahoma Geological Survey maps sinkholes statewide.
What does this sign look like?
A circular or bowl-shaped low spot appears in the yard, under a driveway or next to the foundation, sometimes over days and sometimes overnight. Nearby slabs may crack or drop. Any foundation type can be affected, including slab-on-grade, crawl space and flatwork.
What is a sinkhole?
A sinkhole is an area of ground with no natural surface drainage, so rainwater collects in it and drains underground 1. Sinkholes range from a few feet to hundreds of acres across 1. They are common where groundwater can dissolve the rock below, including limestone, dolomite, gypsum and salt 1. Ground underlain by this kind of rock is called karst 2.
USGS describes three basic types 1:
- Dissolution sinkholes: water gradually dissolves and carries away the rock until a depression forms.
- Cover-subsidence sinkholes: sandy cover soil gradually sifts down into openings in the rock.
- Cover-collapse sinkholes: where the cover contains significant clay, the ground can collapse abruptly, sometimes within hours.
About a quarter of the United States is underlain by rock that can dissolve to form caves and sinkholes 6.
Where do sinkholes occur in Oklahoma?
| Rock type | Main Oklahoma areas |
|---|---|
| Limestone and dolomite | Ozark area of the northeast; Arbuckle Mountains in the south 3 |
| Gypsum and salt | Many parts of western Oklahoma 3 |
Gypsum and anhydrite lie within about 30 meters of the surface across roughly 4 percent of Oklahoma, including the Permian Blaine gypsum of western Oklahoma 4. Gypsum karst can develop fast enough, on a human time scale, to threaten highways and other structures 4. Evaporite karst (karst in gypsum and salt) can form in days, weeks or years and can damage homes, buildings and roads 5. See gypsum karst and sinkholes and Permian gypsum units.
The Oklahoma Geological Survey reports that sinkholes can form slowly or within hours or days, that more were expected in the parts of the state most affected by heavy April 2025 rain, mostly small ones where water flowed under roads and driveways, and that it is mapping sinkhole locations and asking residents to report them 2.
What are washouts and other human causes?
Not every depression is karst. Human activities linked to sinkholes include groundwater pumping, construction, and changes to natural drainage 1, as well as leaking pipes beneath roads and buildings 7. Leaking water mains and faulty drains can erode soil around footings, and underground water scouring one side of a footing can rotate it and displace the wall above 8. These are covered under erosion, undermining and washout voids.
How is it investigated?
- Probing and drilling locate soft zones and voids directly.
- Geophysics. Researchers in western Oklahoma combined electrical resistivity, electromagnetic and seismic methods to map solution cavities in gypsum 4.
- Reporting. Sinkhole locations can be reported to the Oklahoma Geological Survey 2.
Filling options for voids under slabs are described in void and compaction grouting.
Related
- Karst Subsidence & Sinkholes
- Gypsum Karst and Sinkholes
- Erosion, Undermining & Washout Voids
- Northwest (Gypsum Hills)
- Exposed Slab Edge or Void Under Footing
Common questions
Does Oklahoma have sinkholes?
Yes. Limestone and dolomite karst occurs mainly in the Ozark area of northeast Oklahoma and the Arbuckle Mountains, and gypsum and salt karst occurs in many parts of western Oklahoma. The Oklahoma Geological Survey maps sinkholes and asks residents to report them.
Can a sinkhole form quickly?
Yes. Sinkholes can develop slowly or within hours or days. Gypsum karst can form on a human time scale, fast enough to pose a collapse hazard to roads and buildings.
Can a leaking pipe cause a sinkhole?
Water moving underground, including from leaking pipes and mains, can carry soil away and leave voids. Leaking pipes beneath roads and buildings are listed as a human cause of sinkholes.
How are voids under the ground found?
Probing and drilling locate voids directly. Geophysical methods such as electrical resistivity and seismic surveys have been used in western Oklahoma to map cavities in gypsum without drilling every spot.
Sources
- Sinkholes U.S. Geological Survey, Water Science School
- Hazard Mapping Oklahoma Geological Survey
- Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems AAPG Search and Discovery (Oklahoma Geological Survey author)
- Integrated Subsurface Imaging Techniques for Detecting Cavities in Oklahoma Evaporite Karst Geological Society of America
- Evaporite Karst and Engineering/Environmental Problems in the United States (Circular 109) Oklahoma Geological Survey
- How many sinkholes open up in a year? U.S. Geological Survey
- Sinkholes American Geosciences Institute
- Inspecting Foundation Walls and Piers International Association of Certified Home Inspectors (InterNACHI)
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