LOUISVILLE, Ky. (WHAS11) -- Engineers continue their investigation into what caused the giant sinkhole discovered at the Louisville Zoo Wednesday morning, closing the zoo and the nearby Mega Caverns as they continue to work on determining whether the area is safe for the public.
The Mega Caverns had been closed before the sinkhole was even found due to an earthquake reported Tuesday evening in Tennessee. But Jafar Hadizadeh, a professor of geosciences at the University of Louisville, said he does not believe the earthquake and sinkhole are related due to the smaller magnitude and distance of the earthquake. Instead, he said the culprit can be found in the skies rather than under the earth.
"It's probably the wet spell that we've had," he said. "A couple weeks of rain, they can do that in sinkhole areas. They can cause the collapse."
In Kentucky, sinkholes can be common because of its large amounts of limestone. Groundwater and rainwater dissolve the rock underground, which creates spaces and caverns. The ground on top usually stays intact until the space gets too big, which is when they collapse into sinkholes.
"Collapsed sinkholes are always unexpected because you cannot detect them," Hadizadeh said. "You suspect them. And in Kentucky, we know they are there."
Hadizadeh believes this was a collapsed sinkhole, which means the ground sank and collapsed into a cavern that had already been created below it. He said while some sinkholes can be filled in, if crews did that in this case, it would likely add weight and cause more collapses.
"Filling this would not be helpful," he said. "It's just a natural feature, this collapse. There's going to be a cliff and a drop and you've got to leave it alone."
The zoo has announced it will be closed Friday. Both the zoo and Mega Caverns will remain closed until the engineers can determine it is safe.
►Contact reporter Dennis Ting at dting@whas11.com. Follow him on Twitter (@DennisJTing) and Facebook.