The company operating the mine said in a statement there had been “no impact to personnel, equipment or infrastructure,” and the crater has remained stable since its formation three days ago.
It’s not entirely clear how the crater formed, but geologists think it is a sinkhole.
Cristian Zuniga, mayor of the nearby city of Tierra Amarilla, told journalists the hole’s formation was unprecedented. “We ask that the cause be clarified: whether the collapse is the product of mining activity or something else,” he said.
Chile’s National Geology and Mining Service director David Montenegro said experts would seek to determine the cause of the collapse and “ensure that all safety measures are taken to safeguard the lives of workers and communities close to the site.” Montenegro noted the presence of a lot of water at the hole’s bottom, suggesting it played a role in its formation. A 100-meter security perimeter has been erected around the sinkhole.
Sinkholes, collapsed underground cavities, can form in any rock type soluble or erodible by flowing water, like gypsum, salt deposits, but also fine-grained sediments. Sinkholes can be just a meter across, or more than 100 meters wide and deep.
A classic solution sinkhole is formed very slowly by chemical dissolution in solid rock, posing no immediate danger to people. Subsidence sinkholes are far more dangerous, as they form by quick erosion and the sudden collapse of the thin soil cover.
Materials provided by Reuters.