Why Do Sinkholes Collapse? Karst and Pseudokarst Underground Dangers


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Florida Aquifer and Its Sinkhole. Image by SRWMD.

This is how the Florida Aquifer and its sinkhole combine to form a dangerous area. Image by SRWMD.

What Causes Cover-Collapse Sinkholes?

Water is buoyant and generally helps to support the surface layer above a cavity. If large changes in the water table occur causing this buoyancy to expand or contract, a collapse can take place. According to the Suwannee River Water Management District, factors contributing to the water table changes can include more or less rain than usual, drilling a new well, and building above a cavity.

Warning Signs of Sink Holes: What to Watch for

No ready reference on sinkhole prediction is available although the USGS provides geologic maps that identify the risk areas. In an NPR interview by Celeste Headlee, Lewis Land commented: “We could probably make a lot of money if we could predict exactly where and when a sinkhole is going to occur. But in general, we can’t do that.”

There are, however, warning signs. According to the Suwannee River Water Management District, keep an eye out for newly-exposed surface or sagging taking place with anything in the ground, including fence posts, foundations, or trees. In a home, watch for doors and windows that stop closing properly, and cracks in the walls or floor. Look for cracks in the ground surface or pavement outside, as well as small ponds forming where there were none before, or small round patches of greenery that are wilting. Muddy well water and deep narrow holes in the ground that lead to the aquifer are other clues that you’ve got a sinkhole developing near.

Sinkholes Are Dangerous: Stay Away

If you spot any of these warning signs, contact local officials for assistance, and place a fence, rope or tape around any dangerous area, keeping children out of the area. Equally important, do not throw anything into the sinkhole; instead let the experts deal with it. After all, your sinkhole connects with an aquifer, which often where the drinking water comes from. Anything you throw in a sinkhole goes straight into a drinking water supply.


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Morel, L. Documents reveal more details in Seffner sinkhole. (2013). Tampa Bay Times.

Florida Department of Environment Protection. Sinkhole Questions. Accessed September 26, 2013.

Headlee, Celeste. The Science of Sinkholes. (2013). NPR. Accessed September 26, 2013.

Hunter, Dana. Living and Sometimes Dying With Karst. (2013). Scientific American (Blogs). Accessed September 26, 2013.

Moore, W.G. A Dictionary of Geography. 1963. Penguin Reference Books.

Russell, D.J. Role of the Sylvania Formation in Sinkhole Development, Essex County. (1993). Ontario Geological Survey, Ministry of Northern Development and Mines.

Suwannee River Water Management District. Sinkholes. Accessed September 26, 2013.

University of Kentucky. Karst is a Landscape. (2006). Accessed September 26, 2013.

USGS. The Science of Sinkholes. (2013). Accessed September 26, 2013.

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