Sinkholes are an incredible and terrifying natural phenomenon. Suddenly, the ground beneath our feet opens up and consumes whatever happens to be standing in its way. It’s a troubling sight, but how much should you actually worry about them?
What Are Sinkholes?
Sinkholes, as explained by the USGS Water Science School, are an area of ground that has no natural external surface drainage. As rain falls, the water accumulates in the sinkhole then drains into the subsurface, eroding the limestone, carbonate rock, salt beds, and other slightly soluble bedrock forming spaces and caverns below. Eventually, there’s not enough support underground for the land surface and it collapses.
Sinkhole sizes vary from being a few feet wide to covering hundreds of acres, often going more than 30.48m deep, which can be incredibly destructive in areas where there are homes and roads. Some sinkholes retain water fairly well and become naturally occurring ponds.
How Often Do They Occur? And Where?
We don't know how often they occur because there isn't enough data on the natural phenomenon. Many happen in agricultural areas or locations where there aren't any people to keep track, and there's no global sinkhole database to check.
Still, we do know where they occur most often. Sinkholes are most common in areas where the rock below the land surfaces is comprised of limestone, carbonate rock, and salt beds. This is common in America, including in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, Pennsylvania, eastern New York, Indiana, southeastern Minnesota, and parts of South Dakota, Wyoming, New Mexico and Oklahoma.
What Are the Warning Signs of Sinkholes?
Sinkholes form very slowly, so they can be hard to predict, and there may be no warning signs at all. That said, keep an eye out for fresh cracks to the foundation in your home and other buildings, and watch for skewed door frames that won't let your door shut properly. Other signs include a tree in your yard suddenly starting to lean to one side and cracks appearing in the ground outside. If you see those things, avoid the area and do not approach any cracks or impressions on the ground. Contact someone who can investigate the area safely.
Should You Worry About Sinkholes?
Not necessarily, but it depends on where you live. Most sinkholes don't cause fatalities, but it is a possibility -- especially if the collapse occurs direction underneath you without warning. If your home is any of the areas mentioned above, make sure you at least have insurance coverage for sinkholes.
And you should always be on the lookout for the warning signs, even when you're driving in those areas. Many injuries and fatalities occur when people accidentally drive into sinkholes in a road.
For the most part, though, stay vigilant, make sure you're always prepared for an emergency, and don't worry too much about the Earth trying to swallow you up.