Sinkholes are a natural phenomenon that most of us probably aren't too familiar with. In short, sinkholes (or "sinks") are holes that open in the Earth. These may be as small as a car, as large as a house, or even span hundreds of acres. Likewise, some are so shallow that you could easily hop down into them, others are known to be extremely deep (reaching 600 meters/2,000 feet or more).
These beasts have swallowed people, cars, trees, and even entire houses or city blocks.
That said, sinkholes are not terribly common. So there's really no need to fear being randomly consumed by the Earth while you are going for your morning jog. Still, such events have been known to happen. In 2013, a Florida man named Jeff Bush died when a large sinkhole opened near his Tampa home and swallowed him as he slept in his bed.
The 36-year-old's body was never recovered. The sinkhole was just 30 feet wide and 20 feet deep; however, the subterranean cavity disclosed by the sinkhole was more than 100 feet. This made the search rather difficult, and it is also likely that Bush was covered in debris after the fall.
And on August 19, 2015, a sinkhole formed in exactly the same place where Bush was swallowed in 2013.
It may seem surprising to know that, although we know how they form, sinkholes are almost entirely unpredictable.
Sinkholes (also known as “sinks”) are created by water. Most often, these gaping maws form because of extreme erosion taking place beneath the soil. This erosion is often caused by underground rivers, but may result from human activity as well, such as broken pipes.
As you may know, erosion is a slow process, so most sinks generally develop slowly as bedrock is whittled away by water; however, sometimes, when there has been enough erosion and the pressure is just right (or just wrong), the ground will give way all at once—swallowing trees, people, and anything else unfortunate enough to be standing in the immediate area.
And although they are rare, they are more common in certain areas. Since 2010, nearly 300 sinkholes have opened in Florida, leading to the apt name “Sinkhole Alley.”