As if you didn't have enough to worry about, once in a while the earth really does open up and swallow something — or someone — whole. In 2013, a 17-foot-wide sinkhole killed a man in Seffner, Florida while he slept in his bedroom. His body was never recovered. The same sinkhole reappeared in August of this year, reaching a depth of 20 feet.

Sinkholes occur when certain types of rock, such as limestone, come into contact with water and start dissolving, according to the US Geological Survey. When the rock disappears, it leaves behind an empty cave, often underground where you can't see it. If the soil, water or buildings above it are too heavy, they can suddenly collapse or sink into the cave.

Sinkholes can be very large or very small. For example, the Daisetta Sinkhole in Texas is a 900-foot wide and 400-foot deep monster, according to the University of Florida. But even smaller, less noticeable ones can damage your plumbing system or your house’s foundation.

Is your property at risk for potential sinkholes? Consider these points:

  • Cracks in walls and floors, cloudy well water and doors or windows that don’t close properly are possible signs of sinkholes.
  • Twenty percent of the land in the United States has the kind of terrain (known as karst terrain) most vulnerable to sinkholes.
  • New housing developments, artificial ponds and road construction projects that add weight over an existing cavity can trigger one.
  • Pumping out too much ground water from wells or drilling more wells can leave an empty space below your feet.

If a sinkhole appears on your property, the University of Wisconsin has instructions for filling it in.

Lear more about hot to spot a sinkhole, how they form and where they occur in the University of Florida infographic below.

UF Online Infographic: How to Spot a Sinkhole
UF Online B.A. in Geology