The circular hole, resembling a gigantic bomb crater, was discovered on Tuesday by a local boy, according to a statement from the authorities in Bernburg, who have warned further collapses are possible.
The crater, measuring 30 metres across and 40 metres deep, appears to be the result of a collapsed salt deposit, they said. They have closed down the area, which is a disused rubbish landfill, and warned local residents that other parts of the area may also be unstable.
“Further collapses cannot be ruled out,” said a City of Bernburg statement. “Access for the former landfill is strictly forbidden. There is still an acute danger.”
Such sudden collapses are not an unknown phenomenon in the region. Roads have had to be moved in the past because of cave-ins.
Last July, three people were killed when their house collapsed into a lake in the Saxony–Anhalt town of Nachterstedt. The area near the town was extensively mined for lignite, or brown coal, during the 19th century, meaning the ground was shot through with hundreds of tunnels.
Authorities have sealed off the landfill area and blocked a nearby country road while authorities from the State Office for Geology and Mining could investigate, the statement said.
The most obvious cause of the cave-in is that underground ice has thawed after the long winter and the water has dissolved the salt deposit.
The ground is part of an landfill that has been disused for decades.