Buzz
Sinkholes are created when underground cavities close to the Earth's surface collapse. While they often seem inactive, these natural formations can perform some truly remarkable feats.
Beyond unexpectedly swallowing the ground beneath people (and creating dramatic CCTV footage), sinkholes can gradually devour cities and iconic landmarks. Some even generate their own microclimates. These voids often conceal ancient relics and secrets, drawing scientists into perilous explorations. Sadly, they can also harbor more contemporary terrors.
10. New Giant Sloth
In 2009, a professional diver explored a sinkhole located south of Cancun, Mexico. During his exploration, he discovered bones that initially appeared to belong to a cow. However, upon further investigation, he uncovered claws among the ribs, revealing a more intriguing find.
Realizing that cows with claws do not exist, he concluded it was something extraordinary. Experts specializing in sloths identified the remains as a new species of giant ground sloth, weighing up to 500 kilograms (1,100 lb).
The species was given an unusual name: Xibalbaonyx oviceps, which means 'underground claw egghead.' Despite its bovine-like appearance and peculiar name, X. oviceps holds significant scientific value.
Around three million years ago, the Great American Biotic Interchange occurred, allowing land mammals from North and South America to migrate across the continents. In 2017, the egghead specimen provided evidence linking sloths from both regions, shedding light on how these animals spread during this pivotal event.
9. The Six-Story Sinkhole
In 2018, Colin Tremain, a farmworker from New Zealand, stumbled upon an astonishing discovery. While herding cattle, he came across a massive hole stretching the length of two football fields and deep enough to engulf a six-story building. The eerie part? It had formed overnight.
As Tremain considered ways to prevent curious cows from approaching, a group of volcanologists rushed to investigate. The farm sits atop a dormant volcano, and the sinkhole provided a unique window into its geological history.
At the bottom, they uncovered 60,000-year-old volcanic deposits. Above this ancient layer were traces of ancient lakes that once filled the sinkhole, topped with a layer of volcanic ash.
The crater could offer insights into the volcano's past eruptions. However, the exact cause of the sinkhole's formation remains uncertain. It likely resulted from the collapse of an underground cavern's thin ceiling due to heavy rainfall.
8. World’s Largest Cluster
While many sinkholes are man-made, their natural counterparts are much rarer but equally astonishing.
In 2016, researchers exploring northwest China discovered the largest cluster of natural sinkholes ever recorded. This group of 49 sinkholes spread across four counties, covering an area of 600 square kilometers (232 mi).
After four months of intensive exploration through forests and mountainous regions, geologists not only identified the world’s largest sinkhole chain but also uncovered around 50 additional funnels. These ranged from 50 to 100 meters (164–328 ft) in diameter.
Among the 17 large sinkholes, one stood out as the most impressive. This colossal sinkhole could easily conceal the Eiffel Tower, and the Empire State Building could lie horizontally within it without touching its walls. To put it in numbers, it measured 520 meters (1,706 ft) in diameter and reached a depth of 320 meters (1,050 ft).
7. The Bus Stop Incident
In 2015, pedestrians in Harbin, China, were walking along a footpath. Those who kept moving were fortunate, but five individuals standing still were not. They were waiting at a bus stop when a sinkhole suddenly opened beneath them without warning.
The event happened in an instant, leaving no time for anyone to react. A nearby security camera recorded the dramatic scene, showing one woman clinging to an underground pipe, saving herself from falling. The other four dropped about 3 meters (9.8 ft), but all sustained only minor injuries. The woman was quickly rescued.
The cause of the collapse remains unclear, but sinkholes are becoming a significant issue in China. In Jining, another city, sinkholes are so frequent due to extensive mining that five million residents are expected to relocate within this century.
6. The Dead Sea Collection
The Dead Sea is home to over 4,000 sinkholes, with the majority scattered along its western shores, a popular tourist destination.
Bordered by Israel, Jordan, and parts of the West Bank, the Dead Sea has drawn visitors for millennia, drawn by its mineral-rich, hypersaline waters believed to have health benefits. However, the growing threat of sinkholes poses a significant risk, as these massive chasms can open unexpectedly along the shoreline.
The cause of these sinkholes is well understood. The Dead Sea is shrinking due to the diversion of the Jordan River, its primary water source, for human use. Additionally, extensive mining of its salt and minerals exacerbates the issue. As the saltwater recedes, freshwater rises, dissolving underground salt layers and triggering sinkhole formation.
While no fatalities have been reported, the danger is ever-present. Scientists cannot predict where new sinkholes will form, and their frequency is increasing. Some even merge to create massive craters, posing risks to both tourists and local residents.
5. Buckling Oil Fields
In the 1980s, sinkholes began appearing in Wink, Texas, and have continued to spread, highlighting a growing issue in the region's extensive oil fields. The ground is shifting dramatically, causing concern among geophysicists.
This instability stems from human activities. The area, one of the world's largest oil production zones, has experienced decades of oil and gas extraction, carbon dioxide injection, and saltwater disposal wells, all contributing to the problem.
Recent analysis of historical data revealed troubling findings. Some areas have shifted by up to 100 centimeters (40 in), posing a risk to infrastructure like pipelines. Such shifts could lead to environmental disasters, including oil spills.
This area is a vital hub for gas and oil production in the United States, ensuring that operations will persist. However, residents of West Texas are increasingly facing safety concerns due to the ongoing ground instability.
4. City Under Siege
Tehran, the capital of Iran, has recently experienced a surge in sinkholes due to a combination of factors. These issues have led to the sudden appearance of sinkholes across the city.
A prolonged drought has transformed the region into a desert-like environment. Residents in their late twenties and early thirties have only witnessed declining rainfall and expanding sand dunes. This lack of rain has forced Tehran to rely heavily on underground water reserves.
A significant volume of groundwater has been extracted due to another pressing issue—rapid population growth. Tehran's population has surged to 8.5 million, all requiring daily water supplies. Compounding the problem, a substantial portion of this water is used for irrigating fields that are increasingly unproductive.
The consequences are alarming. The excessive removal of groundwater has led to widespread sinkholes and extensive fissures. These collapses endanger homes, businesses, highways, and even the airport, while also damaging critical infrastructure. Residents are justifiably fearful of building collapses, as Tehran is sinking at a rate of 22 centimeters (8.6 in) annually.
3. Modern Mass Grave
Located a few miles outside Mosul in Iraq, the Khasfa sinkhole holds a grim secret—the remains of 4,000 murder victims.
In 2014, ISIL seized control of Mosul and launched a brutal campaign against the city's security forces and police. Captured officers and soldiers were taken to the sinkhole, executed, and discarded into its depths.
Some victims were loaded onto a bus, which was then driven into the deep chasm. Local residents were often forced to witness these atrocities. They reported that the killings began six months after ISIL took over the city, with 2,000 security personnel executed in a single day at the Khasfa sinkhole.
Due to the dangerous conditions, Human Rights Watch monitored the site via satellite, observing the sinkhole gradually fill as the horrors unfolded. This site is considered the largest mass grave in Iraq, surpassing even the infamous ISIL massacre of 1,700 army cadets near Tikrit in 2014, which turned the Tigris River red with blood.
2. Clouds Inside Sinkholes
In southwest China, miners extracting nitrates near the Niubizi tiankeng sinkhole had long suspected something extraordinary lay beneath its 195-meter (640 ft) depth. It took a team of 15 explorers from a caving society to uncover the hidden marvels below.
In 2013, the team descended into Niubizi tiankeng and discovered an extensive underground cave network. The system, dating back to the Ordovician Period (488.3 million to 443.7 million years ago), spanned 42,139 meters (138,251 ft) and reached depths of 441 meters (1,447 ft).
Beyond its impressive scale, the cave system offered breathtaking sights. It housed a lush forest with clear ponds and whitewater rapids, surrounded by towering stalagmites. Most remarkably, clouds and fog filled the air in the aptly named Cloud Ladder Hall, a phenomenon caused by the caves' high humidity.
1. Mysterious Mayan Cenote
The ancient Mayan city of Mayapan, located in southern Mexico, had a population of approximately 17,000 between AD 1150 and 1450.
Due to the arid climate, the city was ingeniously designed to incorporate 40 cenotes, or water-filled sinkholes. However, one cenote, Sac Uayum, was deliberately excluded by the city wall, which curved around it, while another nearby cenote was included.
In 2014, researchers investigated why this valuable water source was avoided. A diving team discovered two chambers containing at least 15 human skulls and various skeletal remains, including men, women, and teenagers. The remains were confirmed to be Mayan, with one woman’s skull showing signs of cranial flattening, a common practice for infants at the time.
The skeletons bore no signs of sacrificial rituals or other explanations for their presence in Sac Uayum. Since the Mayans typically buried their dead near or inside their homes, it is possible these individuals were plague victims. This would account for their placement outside the city and the cenote’s exclusion as a water source.
