Sinkholes—those terrifying natural phenomena known for gulping down unsuspecting houses, bridges, or even Corvettes—have been a hot topic in the news lately. Most of these newsworthy cave-ins are of the "cover-collapse" variety, in which soil beneath the surface begins to shift downward, leaving behind an increasingly large air pocket beneath a thin bridge of soil that manages to hold together until one day it doesn't, and suddenly: sinkhole.
Unlike earthquakes and hurricanes, sinkholes cause damage that is usually concentrated in a single place: namely, the new, gaping opening in what used to be a grassy field or intact asphalt highway. This destruction is no picnic for residents of the surrounding area, but for everyone else, it serves as a fascinating reminder of the Earth's dangerous potential.
1. Ottawa, Canada
Ottawa residents were disappointed on February 21, 2014, when their proposed celebration of one year's construction work on a new light rail transit system turned into a press conference about the hole that put a halt to their plan. There's no official diagnosis of exactly what caused dirt to begin showering down on excavation crews working to clear an underground tunnel for transit, but it's a safe bet that all that digging around couldn't have helped. Gravity is a tricky force to manage, and with nothing beneath it for support, all that surface dirt needed somewhere to go: thus, a sinkhole.
2. Beijing, China
In another example of human construction projects gone awry, the city of Beijing found itself with a sinkhole on its hands after improper procedure caused an underground water pipe to burst. The 16-foot by 16-foot hole filled with water, diverting the supply for almost 300 households in the area and creating a very unappealing kind of urban swimming pool.
3. Xi'an, Shaanxi, China
A broken water pipe strikes again in another Chinese province, causing the collapse of a two-lane road—but, luckily, no casualties.
4. Clermont, FL
Disney World enthusiasts at Florida's Summer Bay Resort had their vacations rudely interrupted by a sinkhole in August 2013 that caused serious structural damage to two buildings housing roughly 105 people. Though their holiday guidebooks probably didn't warn them, Florida is no stranger to such upsetting events: the state's frequent rainfall makes its underlying bedrock more prone to dissolve even as the ground's surface remains intact, leading to a nasty surprise when what seemed solid just a minute before suddenly gives way. In this case, a quick-thinking security guard (who was probably up on his sinkhole science) reacted to reports of unexplained loud noises and cracking windows by evacuating all the guests, giving them plenty of time to get away from the disaster area safely.
5. Montreal, Canada
Though a sinkhole that can take down a construction vehicle seems plenty big, this interruption on Montreal's Saint-Catherine Street is a baby compared to the world's biggest sinkholes. The Qattara Depression just west of Cairo, Egypt measures 75 miles across at its largest point, a distance this tractor would have taken hours to travel.
6. Xi'an, Shaanxi, China
The frequency of sinkhole stories coming out of China has many of its citizens blaming the nation's emphasis on rapid urbanization coupled with inadequate training for construction workers, leading to a weak infrastructure that contributes to sinkholes like the one that swallowed a cement truck. Japan experienced a similar problem about 20 years ago, when hasty construction in Tokyo caused approximately 20 sinkhole disasters a year; since the city began more stringently investigating the underground landscape using radar technology, that number has dropped to about two per year.
7. Toledo, OH
Lt. Matthew Hertzfeld/Toledo Fire and Rescue/Reuters
Pamela Knox must have had the most interesting story to share around the dinner table on July 3, 2013, after she drove straight into a sinkhole that opened up right in front of her eyes. The driver ahead of her just managed to drive past the collapsing bit of roadway, but there was no way for Knox to do the same. She was, at least, able to climb up a ladder to the surface, shaken but unharmed.
8. Loudi, Hunan, China
A Chinese motorcyclist experienced another near-miss in a sinkhole that appeared in the wake of a large truck: the man fell in, but was rescued promptly and, while injured, survived.
9. Shenzhen, Guangdong, China
Not all sinkhole victims escape. Here, rescue workers retrieve a body from a caved-in roadway. Such deaths are rare, but when a sinkhole strikes, there's no way to avoid it: reported incidents from Beijing, Taiwan, Idaho, and Utah have all involved victims who were near-instantly lost when the ground gave way beneath them.
10. Chicago, IL
"April showers" took a more sinister turn in Chicago last year. Instead of May flowers, they brought school closures, air travel delays, and a sinkhole that swallowed three cars. Major flooding in the South Side area put pressure on an old water main dating from 1915, which gave way and contributed to the rapid erosion beneath street level.
11. Xi'an, Shaanxi, China
Although no official cause was determined for this particular sinkhole, it's likely another run-of-the-mill case of erosive activity, poor construction, or broken pipes—unlike one tragic accident in Idaho caused by a vast network of gopher tunnels.
12. Toowoomba, Australia
Brisbane residents put up sandbags around their homes to prevent the onslaught of area flooding, but nothing could prevent a gaping sinkhole from forming just west of the city.
13. Schmalkalden, Germany
Officials from the German town of Schmalkalden, population approximately 20,000, declared their intention to fill a sinkhole measuring 98 feet across and 65 feet deep with gravel. In most other instances, sinkholes in non-residential areas are usually left to their own devices; over time, sinkholes will usually self-correct by filling with eroded soil from the surrounding area. In some cases, the hole fills up with water instead, creating a pond.
14. Dachegnqiao, Ningxiang, Hunan, China
The worst sinkholes are the ones that aren't yet satisfied. Onlookers near the Dachegnqiao sinkhole were careful not to get too close, since the crater was already 492 feet wide at the time of this photo and continued to grow each day.
15. Les Arcs sur Argens, France
Rainfall of around 14 inches in just a few hours and its location near Le Real River spelled sinkhole disaster for this town center.
16. Guatemala City, Guatemala
More than 94,000 people had to be evacuated in a sinkhole disaster of epic proportions caused by Tropical Storm Agatha in 2010. Rescue efforts on such a large scale were made even more difficult by the destruction of roads and highway bridges leading out of the city. There were significant casualties.
17. Caracas, Venezuela
In December 2010, thousands of Venezuelans were forced to flee their homes—and 21 people were killed—amid landslides and river flooding, which also contributed to this sinkhole in the Gran Marical de Ayacucho highway in the state of Miranda outside Caracas.
18. Hefei, Anhui, China
The 6-foot sinkhole here couldn't quite consume a building, but it easily took down a taxi and a few motorbikes, with one more car teetering on the edge.
19. Nachterstedt, Germany
A peaceful lakeside residence disappeared into the water one Saturday morning in an eastern German village. The "lake" was the converted remainder of an old coal mine, and this instability may account for the 350 meters of shoreline that disappeared along it.
20. Guangzhou, Guangdong, China
Another car fell prey to a sudden road collapse in China's Guangdong province, but no casualties were reported. Although this is a fairly shallow hole, the Chinese have a special name for extremely large craters exceeding 820 feet in depth and/or width: "tiankengs," or "sky holes."
21. San Sebastián, Spain
A 2008 storm along the Bay of Biscay, on the Spanish coast near the French border, sunk boats moored along the Paseo Nuevo, or "New Promenade."
22. Guatemala City, Guatemala
A smaller sinkhole than the one that put Guatemala's capital city in global headlines in 2010, this 2007 crater nonetheless consumed a number of homes and resulted in three residents reported missing.
23. Nagapattinam, India
This shot of Indian locals looking suspiciously into the pit left behind by tsunami damage in 2004 demonstrates an appropriate level of wariness when dealing with sinkholes: in the same way that lightning (despite the old adage) is more likely to strike the same location multiple times, the presence of one sinkhole often indicates an area's overall unstable topography, which may contribute to even more unpleasant geologic surprises in the near future.
24. Gallipoli, Italy
Italy is one of a handful of countries around the world whose karst topography—that is, land dominated by water-soluble rocks like limestone, which easily dissolve to create irregular landscapes—makes it susceptible to sinkholes born of natural causes. Florida is one of the United States' most notable karst areas; other such vulnerable regions include Mexico, Belize, China, Russia, Slovenia, and Croatia.
25. Nanchang, Jiangxi, China
Sinkholes don't often have such neat edges as this collapsed segment of Shunwai Road in Nanchang. Officials announced plans to investigate causes of the cave-in, but sinkholes can be as unknowable as they are dangerous.