In the last few years, news of unexpected sinkholes swallowing cars, houses and people have made headlines with disturbingly high frequency. These reports are mainly coming from Florida, the U.S., where almost the entire state is karst terrain (made of limestone), which means it has the potential for sinkholes. Mexico, Belize and parts of Italy and China are also karst area, but the phenomenon of sinkholes suddenly appearing in apparently stable grounds is mostly American. Experts estimate thousands of sinkholes form every year in Florida alone.
Sinkholes form when water flowing underground has dissolved rock, mostly limestone and sometimes clay, below the surface, leading to the formation of underground voids. When the surface layer can no longer take the weight of whatever that’s above, it collapses into the void forming sinkholes. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface can occur.
A giant sinkhole caused by the rains of Tropical Storm Agatha is seen in Guatemala City on May 31, 2010. More than 94,000 people were evacuated as the storm buried homes under mud, swept away a highway bridge near Guatemala City and opened up sinkholes in the capital. (Casa Presidencial / Handout / Reuters)
An aerial view of the damaged Gran Marical de Ayacucho highway in the state of Miranda outside Caracas December 1, 2010. Thousands of Venezuelans fled their homes after landslides and swollen rivers killed at least 21 people and threatened to cause more damage. (Photo by Miranda Government/Reuters)
A construction vehicle lies where it was swallowed by a sinkhole on Saint-Catherine Street in downtown Montreal, August 5, 2013. (Photo by Christinne Muschi/Reuters)
Pamela Knox waits for rescue after a massive sinkhole opened up underneath her car in Toledo, Ohio in this July 3, 2013 handout photo provided by Toledo Fire and Rescue. Toledo firefighters later rescued Knox without major injuries. Fire officials told a local TV station that a water main break caused the large hole. Picture taken July 3, 2013. (Photo by Lt. Matthew Hertzfeld/Toledo Fire and Rescue/Handout via Reuters)
A stranded car is hoisted from a collapsed road surface in Guangzhou, Guangdong province, September 7, 2008. The road collapsed on Sunday afternoon and trapped the car in a hole, which measured 5 meters (16.4 feet) in depth and 15 meters (49.2 feet) in diameter, local media reported. Further investigation is underway. Picture taken September 7, 2008. (Photo by Reuters/China Daily)
An aerial view shows the debris of a residential building and a destroyed road in the village of Nachterstedt, July 18, 2009. Three residents were missing in the eastern German village of Nachterstedt after their lakeside home and another building suddenly collapsed early Saturday into the water. A 350-metre stretch of shoreline gave way next to an old open-cast coalmine converted to a lake, about 170 kilometres south-west of Berlin. (Photo by Reuters/Gemeindeverwaltung Nachterstedt)
Rescue workers remove a bus with a crane from a Lisbon street hole November 25, 2003. The bus was parked on a Lisbon street when the ground began to open up and gobble it. No casualties were reported. (Photo by Jose Manuel/Reuters)
A truck is seen in a hole after part of the structure of a bridge collapsed into a river in Changchun, Jilin province May 29, 2011. Two truck passengers were injured, while the cause of the accident is still under investigation, local media reported. (Photo by Reuters/China Daily)
Cars lie in a sinkhole, caused when a road collapsed into an underground cave system, in the southern Italian town of Gallipoli March 30, 2007. There were no injuries in the overnight incident, according to local police. (Photo by Fabio Serino/Reuters)
A giant sinkhole that swallowed several homes is seen in Guatemala City February 23, 2007. At least three people have been confirmed missing, officials said. (Photo by Reuters/Stringer)
A large sinkhole opened on East Monument Street in Baltimore in summer 2012. The sinkhole appeared above a 120-year-old drainage culvert after heavy rains, causing evacuations and closing the road. (Algerina Perna/Baltimore Sun Photo)