Often preceded by heavy rains, the formations can cause destruction and, in some cases, cost lives.
Nov. 20, 2014 A sinkhole is seen two miles to the east of the Solikamsk-2 mine in the Perm region of Russia. The sinkhole, stretching over 100 feet across, was found at an abandoned mine and increased concern about the future of the mine because a sinkhole in 2006 forced another Uralkali operation to shut permanently. Uralkali is the world’s top potash producer. Uralkali/via Reuters Buy Photo