Another sinkhole has appeared on Route 202 not far from King of Prussia Mall, forcing a sinkhole-related closure on a section of the same road for the second time in six months, write Nick Vadala and Michelle Myers for The Philadelphia Inquirer.

Sinkholes are underground cavities usually caused by water erosion. Most commonly, they show up in areas where the bedrock is composed of materials that can be dissolved by groundwater, such as limestone.

“Once it breaks down, it causes a void,” said PennDOT spokesperson Brad Rudolph. “Eventually, those voids collapse when something heavy gets on it.”

The King of Prussia area is especially susceptible to sinkholes as it sits atop what is referred to as “karst” by geologists. Karst is a landscape of limestone.

Additionally, since limestone does not collapse on its own, usually water infiltrating the bedrock somewhere. Crews are currently trying to determine where that is happening to seal it up and limit future sinkhole-related issues.

“The geological layout of this area is challenging,” said Rudolph. “They’re looking for any kind of water infiltration to figure out what is going on here.”

Read more about sinkholes in The Philadelphia Inquirer.

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