That giant gaping hole on the Southside of Chicago? It may not be a sinkhole after all

April 18, 2013

A 40-foot hole opened up on a residential street on Chicago’s South Side. It swallowed up three cars and a man who suffered non-life-threatening injuries. Many are calling it a sinkhole. But that might not be quite right.

Anthony Randazzo is professor emeritus at the University of Florida’s geological science department and president of Geohazards, Inc, a business that consults on sinkhole issues all around the world.

He says that the 40-foot hole is actually a giant pothole.

“Unfortunately, journalists don’t like to be told what they have is a pothole and not a sinkhole because that’s far less glamorous,” he said.

Randazzo said sometimes companies that fix these kinds of problems also misuse the term.  “Sinkhole” sounds far more terrifying than “pothole” and so they can charge more to fix the issue.

Here’s the real difference according to Randazzo:

Water chemically dissolves limestone, and other similar stones, over many years, forming underground caverns. If one of those caverns collapses, then you got yourself a sinkhole.

In Chicago, a water main broke, perhaps due to the extreme downpour. That physically-- not chemically which is key-- eroded the soil. The result was a pothole.

In Illinois, we don’t have much limestone, so true sinkholes are unlikely. They are more common in places like Florida, where limestone is present.

But don’t be deceived, said Randazzo, potholes can be a real problem for big cities.

“There is a rapid deterioration of infrastructure in major cities,” said Randazzo. “You can expect to see more of this.”

If potholes don’t sound quite terrifying enough to describe the pictures and videos you’ve seen today, feel free to tweet me your alternative titles at @shannon_h or leave them in the comments.