Sinkholes are the culmination of a process that can occur over centuries or even millenniums. When rainwater seeps into the ground, the acids in it gradually erode particular types of bedrock — limestone or sandstone, for example. Natural cracks and cavities in the bedrock slowly expand, and the soil above it begins to fall through. At first, the upper layers can still bear the weight of the buildings above them. But eventually, as the sediment slips through the cracks like sand through an hourglass, the ground gives way. Heavy rainfall can contribute to a sudden collapse.

Florida is especially prone to sinkholes — more so than any other state — because it is built on limestone. The composition of the sediment above the bedrock is also a factor, making some parts of the state more unstable than others. Central Florida, including the Orlando and Tampa areas, is at the greatest risk; parts of Northern Florida are also particularly vulnerable. Land O’Lakes is about 20 miles north of Tampa, in a region of the state known as Sinkhole Alley.

Fatalities from sinkholes are very rare. But in 2013, one swallowed up a man, Jeffrey Bush, as he lay in bed in Seffner, Fla., east of Tampa. His body was never recovered.