LOUISVILLE, KY (WAVE) – Officials with the Louisville Zoo and Mega Caverns announced Friday afternoon that both attractions would remained closed this weekend as engineers continue to probe the massive sinkhole that was discovered Wednesday on zoo property.
Due to rain in the forecast, additional steps have been taken to keep water out of the cavern.
The Tennessee earthquake Tuesday night did initially close the Mega Cavern before the sinkhole was discovered, but a University of Louisville Geologist told WAVE 3 News he does not believe the earthquake caused that sinkhole. He, like others, believes it’s weather related.
“It’s probably the wet spell," UofL Geo Sciences Professor Jafar Hadizadeh said of the sinkhole, which was 90 yards long and 60 yards wide. “We’ve had a couple of weeks of rain; they can do that in sinkhole areas.”
Fortunately the sinkhole happened on an undeveloped and unoccupied area of the Louisville Zoo away from the animals.
Louisville Zoo spokeswoman Kyle Shepherd provided and update on the animals.
“All the animals have been monitored and we continue to monitor them and we haven’t noticed any behavior changes," Shepherd said.
Just to be safe, the Zoo and Mega Caverns has a large team of geo-tech and mining engineers investigating both the above ground and underground. As for the neighbors, Emergency Services Spokesman Mitchell Burmeister said there are no dangers.
“Businesses and homes - anything in that adjacent area has been determined to be safe," Burmeister said. "Residents shouldn’t be worried.”
There are two types of sinkholes: a solution sinkhole and a collapsed sinkhole. Solution is usually oval or circular at the surface. In a collapsed sinkhole, the ground sinks and collapses into the cavern taking its shape.
Professor Hadizadeh said the Corvette Museum sinkhole in Bowling Green in 2014 started as a solution but evolved into a collapsed sinkhole. He believes the one discovered above the Mega Cavern at the Zoo is a collapsed sinkhole. If that’s the case, he said filling it might not be a good idea.
“Filling this would not be very helpful," Hadizadeh said. "It’s just become a natural feature. This collapse, it’s going to be a cliff and a drop and you got to leave it alone.”
“Because filling it is basically more weight and it might collapse into the second deck down there that possibly exists," Hadizadeh explained.
The professor said Kentucky limestone is a factor in sinkhole problems in the Commonwealth. Whenever there are heavy rainfalls, he said we experience all kinds of natural hazards, everything from mudslides to sinkholes.
“Limestone is the type of rock that can dissolve when it is a certain grade of it. You’ve got to have 60 percent or more of the limestone made of pure Calcite,” Hadizadeh said. “When that’s the case, that dissolves in rainwater and soil water.”
While the entertainment area of Mega Cavern was closed, Louisville Underground storage did re-open Thursday.