Water Q&A: My uncle's house was swallowed by a sinkhole!

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Find out why sinkholes occur, often suddenly.

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My uncle's house was swallowed by a sinkhole!

Water Questions and Answers

Luckily this is rare, but items like this show up in the news from time to time. Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces then a sudden collapse of the land surface can occur. These collapses can be small or they can be huge and can occur where a house or road is on top.

Humans can also contribute to sinkholes. If large amounts of groundwater are pumped from an area that is composed of a thick layer of fine-grained material then the land can become more compacted once the water is removed. In other words, the water keeps the soil from settling, and once the water is gone, the soil settles — too bad if there is a house on top.

Some parts of the country are more susceptible to sinkholes, like places where the land is underlain by limestone that can be dissolved by groundwater. Also, a house could be sitting on a salt bed that dissolves, leaving a cavern in the ground. Some homeowners have become cave-dwellers overnight!