. People visit "The Gateway to Hell," a huge burning gas crater in the heart of Turkmenistan's Karakum desert, on May 3, 2014. The fiery pit was the result of a simple miscalculation by Soviet scientists in 1971 after their boring equipment suddenly drilled through into an underground cavern and a deep sinkhole formed. Fearing that the crater would emit poisonous gases, the scientists took the decision to set it alight, thinking that the gas would burn out quickly and this would cause the flames to go out. But the flames have not gone out in more than 40 years, in a potent symbol of the vast gas reserves of Turkmenistan, which are believed to be the fourth largest in the world.
. Workers use a crane to extract the 1993 40th Anniversary Chevrolet Corvette from a sinkhole at the National Corvette Museum in Bowling Green, Ky., on March 3. The 40th Anniversary Corvette, along with seven other Corvettes, fell into the sinkhole on Feb. 12.
. A 22-ton Los Angeles Fire Department fire truck protrudes from a sinkhole on Sept. 8, 2009 in the Valley Village neighborhood of Los Angeles. Firefighters were dispatched to investigate an early morning call about flooding on a residential street when the driver saw a large amount of water in the darkness. The driver was backing up when the truck fell into the sinkhole, apparently caused by a broken 6-inch cast iron pipe. The firefighters were not hurt in the accident.
. A backhoe is swallowed by a sinkhole in Montreal on Aug. 6, 2013. A Montreal business-owner says city officials ignored his warnings that there was a problem before the sinkhole swallowed a backhoe. The backhoe had started to chip at asphalt near the corner of Ste-Catherine and Guy streets when the ground crumbled beneath it and the heavy machine tumbled in. The driver of the backhoe was not injured but was taken to hospital to be checked out as a precaution.
. People gather around a huge sinkhole in the village of Sanica, Bosnia on Nov. 21, 2013. The vanishing pond was some 65 feet in diameter and about 30 feet deep. Now, the "abyss" as the villagers named the dry sinkhole, is some 165 feet wide and 100 feet deep. Scientists say it is not an uncommon occurrence that ponds and small lakes disappear. It could be caused by drying underground waters, or changes in soil drainage due to agricultural irrigation.
. A truck is stranded in a sinkhole in the middle of a road in Wuzhou city, south Chinas Guangxi Zhuang Autonomous Region, on Aug. 14.
. An aerial view of the Great Blue Hole, a popular diving site that is part of Belize’s barrier reef, in this undated photo The Blue Hole is 1,000 feet across and 400 feet deep. It’s a large submarine sinkhole, like a funnel, surrounded by a ring of coral and filled with marine life. The variety of colors indicate various depths of water and coral reef formations.
. A man inspects a sinkhole inside a house on July 19, 2011 north of Guatemala City. When neighbors heard the loud boom overnight they thought a cooking gas canister had detonated. Instead they found a deep sinkhole the size of a large pot inside the home. Guatemala City, built on volcanic deposits, is especially prone to sinkholes, often blamed on a leaky sewer system or on heavy rain.
. A utility worker examines a sinkhole that arose when a broken water main led to the collapse of part of Friendship Blvd. on Dec. 3, 2010, in Chevy Chase, Md. No one was reported injured in the resulting car accident.
. A sinkhole covers a street intersection in downtown Guatemala City on May 31, 2010. A day earlier authorities blamed the heavy rains caused by tropical storm Agatha as the cause of the crater that swallowed a a three-story building but now say they will be conducting further studies to determine the cause.
. A car at the bottom of a sinkhole caused by a broken water line in Toledo, Ohio on July 3, 2013. Police say the driver, 60-year-old Pamela Knox of Toledo, was shaken up and didn't appear hurt but was taken to a hospital as a precaution.
. A view of a sinkhole that opened a few days earlier in Natal, Brazil, on June 22. The sinkhole, caused by recent rains, swallowed cars and damaged the homes of some 150 families living in a poor neighborhood in the northern Brazilian city that's one of 12 which hosted the World Cup matches.
. Workers from Dave's Truck Repair try to figure out how to tow a waste disposal truck out of a sinkhole after a road collapsed in North Guilford Hills near Chambersburg Pa., on June 20, 1997. The truck, owned by Waste Management Co. of Greencastle, was on its regular route when the road gave way, startling area neighbors. The driver and a passenger were not injured.
. A local resident throws a stone into a sinkhole near Qingquan primary school in the town of Daichengqiao in Hunan province, on June 15, 2010. The hole, 492 feet wide and 164 feet deep, destroyed at least 20 houses. No casualties were reported and the reason for the appearance of the hole was unclear, local media reported.
. A car sits in a giant sinkhole in Duluth, Minn., on June 20, 2012. Residents evacuated their homes and animals escaped from pens at a zoo as floods fed by a steady torrential downpour struck northeastern Minnesota, inundating the city of Duluth, officials said.
. People gather around a huge sinkhole in the village of Sanica, Bosnia, on Nov. 21, 2013.