Foundation Repair GuideFree, source-cited foundation information

Sinkholes and Karst: When the Ground Itself Is the Problem

Last reviewed October 28, 2026 · 2 sources cited

Most foundation movement is slow and caused by soil moisture. Sinkholes are different: they come from rock dissolving underground, and the surface can look fine until it suddenly does not. They are regionally concentrated, and the right response is geological and engineering, not only structural repair.

How sinkholes form

The U.S. Geological Survey explains that sinkholes form where bedrock such as limestone, carbonate rock or salt beds is dissolved by circulating groundwater. Underground spaces and caverns develop, and the land often stays intact until those spaces grow too large, and then the surface can collapse. Human activity can also trigger collapse: groundwater pumping, construction, changes to drainage and heavy new loads such as ponds.[1]

Three types

  • Dissolution sinkholes form gradually as rock dissolves.
  • Cover-subsidence sinkholes form gradually where the covering sediment is sandy.
  • Cover-collapse sinkholes can open abruptly, sometimes within hours, where the covering sediment contains significant clay.

(Types as described by USGS.[1])

Where it happens

USGS says the most damage from sinkholes tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania, and notes this describes damage rather than sinkhole counts. It also says evaporite rocks such as salt, gypsum and anhydrite underlie about 35 to 40 percent of the United States, though often at great depths.[1] State geological surveys publish karst and sinkhole maps for their regions; start with yours.

Signs to take seriously

The USGS page we reviewed does not list warning signs. Reports commonly describe new depressions or circular cracks in the ground, ponds or water that suddenly drains, exposed soil voids, and sudden cracking of walls or floors in the same area. These are general descriptions, not USGS statements, so treat them as reasons to call a professional, not as a diagnostic list.

What repair involves

Sinkhole remediation is geotechnical work: investigating the void, stabilizing the ground (by grouting or other methods chosen by the engineer) and then repairing the structure, often with deeper underpinning. This is different from a routine leveling job, and it is the clearest case where an independent geotechnical and structural engineer should lead. See do you need a structural engineer?

Common questions

Which states have the most sinkhole damage?

USGS says damage tends to be greatest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania.[1]

What causes a sinkhole?

Dissolution of soluble rock by groundwater, sometimes triggered by pumping, construction or changes in drainage, per USGS.[1]

Does homeowners insurance cover sinkholes?

Standard policies often exclude sinkhole and earth movement, though details vary by state and policy. The California Department of Insurance, for example, says standard California policies generally exclude sinkhole and earth movement losses.[2] Read your own policy.

Foundation Problems by Region: Clay, Frost, Karst and High WaterWhich foundation hazards are tied to soil, climate and geology, and where to check your own risk.Does Homeowners Insurance Cover Foundation Repair?What standard policies exclude, the exceptions that sometimes apply, flood and sinkhole coverage, and how to handle a claim.Do You Need a Structural Engineer for Foundation Repair?When an independent engineer is worth hiring, what they evaluate, and how it differs from a contractor's inspection.Signs of Foundation Problems: What to Look For Inside, Outside and BelowA room-by-room and outside checklist of the signs that suggest foundation movement, and what does not.

Sources

Figures and claims marked with a number come from these sources. Dates are the publication or last-update dates shown by the publisher, where one was shown. Older sources are flagged in the text.

  1. Sinkholes (USGS Water Science School). U.S. Geological Survey; page dated September 17, 2026.
  2. Fact Sheet: Coverage for Flood, Mudflow, Mudslide, Landslide or Sinkhole Losses. California Department of Insurance; 2018 file date, no other date shown.California-specific. Other states' policies and rules differ; read your own policy.