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Giant Chile sinkhole opens up new debate on mining

Human activities like mining, construction, excavations, and even heavy traffic can lead to sinkholes, say experts

By Kiran N. Kumar

A giant sinkhole of 82 feet in diameter, or roughly the width of the White House, just opened up in an agricultural area outside of the town of Tierra Amarilla in Chile. It measures about 656 feet in depth with plenty of water, according to the country’s National Service of Geology and Mining (Sernageomin).

Usually sinkholes form when water dissolves surface rock of limestone that is easily eroded, or worn away, by water underneath the soil. They occur after heavy rainfall when the rock beneath the surface soil is limestone.

The world’s deepest sinkhole in Chongqing, China, measuring 2,172 feet deep, is one such and another huge sinkhole was similarly formed in the limestone mountains of Nongle in Guangxi Zhuang.

Read: Why did Earth record shortest day ever on June 29? (August 2, 2022)

It measures 656 feet long, 328 feet wide and 387 feet deep and even deeper at 1,476 feet when measured from the access point on the mountain ridge.

In Mexico, known as cenote, these sinkholes form when the roof of an underground cave collapses, exposing the water to the surface. Spread over the Yucatan Peninsula of Mexico, Mexico has more than 2,000 cenotes, which cater to the need for freshwater there. Ancient Mayans believed cenotes were passageways to the mysterious world beneath.

In the United States, a large sinkhole formed in May 2008 in Daisetta, a suburb of Houston, when an underground mound of rock salt gave way, swallowing several cars, oil drilling equipment, and oil tanks. In just one day, it grew up to 656 feet in diameter and 246 feet deep.

Similarly, the land near the Dead Sea in the Middle East is prone to sinkholes due to rock salt that easily dissolves in water, turning dangerous to tourists and scientists alike

Chile Sinkhole
But the latest Chile sinkhole in the plot owned by the Alcaparrosa copper mine, an arm of the Canadian company Lundin Mining, has puzzled geologists to check further whether it has anything to do with the contentious mining operations in the region.

Tierra Amarilla’s mayor Cristóbal Zúñiga told Ciudadano ADN Radio that the community living near the mine has always feared about the mining operations nearby.

“Today it happened in a space that’s an agricultural property, but our greatest fear now is that this could happen in a populated place, on a street, in a school.”

The Chilean sinkhole is likely to open up a new debate on human activities. Louisiana has already reported that sinkholes are forming from abandoned mines.

In Florida, sinkholes are attributed to underground voids and drainage systems carved from the carbonate rocks throughout the state. When the overlying layers of ground collapse into these voids, sinkholes form.

Besides mining, over extraction of water was blamed when a strange hole of about 30 feet wide opened up in the farmland behind a house in Santa María Zacatepec, a small town near the city of Puebla, in central Mexico on May 29, 2021, turning it into a tourist place for selfies.

Read: Giant Sinkhole Swallows Chilean Land Owned By Canadian Mining Company (August 3, 2022)

Though Conagua — the National Water Commission, denied that the hole was due to over extraction of water by an aquifer, a retracted scientific report connected the sinkhole, in part, to the “intense subterranean water usage observed over the last 15 years in the zone of Santa María Zacatepec.”

Drilling new water wells, over-withdrawing groundwater, artificially creating ponds of surface water and even dams could cause formation of sinkholes, but other human activities like mining, construction, improperly compacting the soil after excavations, and even heavy traffic could no less result in sinkholes over a period of time, say experts.

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