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Sinkholes: warning signs and safety

Emergency numbers differ by country. This page uses 911, the number for the United States and Canada. Many other countries use 112, 999, or another number. Find the number for your country.

Sinkholes are ground depressions caused when underground water dissolves soluble rock (such as limestone or salt beds), leaving empty caverns that collapse under surface weight.

Do this now

  1. If you see ground cracking or sinking rapidly under your home or vehicle: evacuate immediately.
  2. Call your local emergency number (911 in the United States, 112 in Europe, 999 in the United Kingdom) and local emergency management office.
  3. Keep people and vehicles far back from the edges of any expanding depression.
  4. Shut off gas and main water supplies if safe to do so from outside the hazard area.

Warning signs of an impending sinkhole

Sinkholes can form gradually or open up suddenly. Watch for these structural warning signs on property:

  • Fresh cracks in interior drywall, plaster, or exterior brickwork.
  • Doors and windows that suddenly stick, jam, or will not close.
  • Circular depressions forming in lawns, gardens, or paved driveways.
  • Fences, utility poles, trees, or mailboxes leaning at odd angles.
  • Sudden appearance of muddy or cloudy water in well water systems.
  • Unexplained exposed foundations or soil pulling away from house walls.

What to do if a sinkhole opens on your property

  • Evacuate the area: Get all family members and pets out of buildings near the depression immediately.
  • Fence or rope off the collapse: Keep neighbors, children, and onlookers away. Sinkhole edges are unstable and can crumble without warning.
  • Do not fill the hole yourself: Throwing trash or soil into a sinkhole can contaminate underground aquifers and worsen collapse.
  • Contact emergency services: Notify local fire or police departments, city building inspectors, and your home insurance provider.

Driving safety near sinkholes

If a road collapses in front of your vehicle while driving: - Stop immediately, put the car in reverse if safe, and back away from the collapsing section. - Turn on hazard lights to warn other drivers. - Never drive across a flooded road or sagging pavement near suspected sinkholes.

... note "Geological hazard tracking" Geological surveys (such as the USGS in the United States) maintain maps of Karst topography and sinkhole risk zones. Check local geological maps if buying a home in high-risk areas.