Scary Guatemalan Sinkhole

When I first saw this picture, I thought it was fake:

It appears to be real.

Apparently, the city sits on top of a Karst formation. The underlying limestone is highly soluble to underground water. As the underground water flows, the limestone is eroded, creating a cave. The Mammoth Caves in Kentucky is Karst Geology (.pdf).

In the sinkhole picture, the groundwater burst through the roof of the underground cave, letting the soil fall in and eventually creating a collapse sinkhole. Now it’s a portal into a deep underground cavern.