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
Hornslet wind-turbine collapse which bent in the direction of the wind. The top half of the tower then sheared off at the bend and fell to the ground. The base of the tower remained standing. The debris of the turbine flew 200–500 metres away. No injuries were caused. The collapse was filmed from a nearby farmhouse. The film was shown on several TV stations and is available online. The turbine was out of service until June 2008 and was eventually replaced by a new wind turbine of the same design. Hornslet wind-turbine collapse The Hornslet Wind Turbine Collapse was a spectacular collapse of