Sinkhole urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole. Sinkholes tend to occur in karst landscapes. Karst
Egma Sinkhole Egma Sinkhole EGMA Sinkhole (), a.k.a. Peynirlikönü Sinkhole, is a sinkhole and the deepest cave in Turkey. It is located at Sugözü village of Anamur, Mersin. The sinkhole is deep and long. EGMA stands for Evren Günay - Mehmet Ali Özel Sinkhole. Beginning in 1993, the cave was being explored by BÜMAK (Boğaziçi University Speleological Society). A flash flood caused Mehmet Ali Özel to lose his life inside the cave in 2001. In 2004, with the help of members of the Bulgarian Speleological Federation, the BÜMAK team recovered Mehmet Ali's body and also reached the deepest point of the cave.