View of a large sinkhole near Mina Alcaparrosa, in Tierra Amarilla, Atacama region DPA via Europa Press
Geomechanics experts are about to solve the mystery of how the gigantic sinkhole that appeared a few weeks ago in Tierra Amarilla (Atacama region), 800 kilometers north of Santiago. The well was extended on land at Lundin Mining’s Ojos del Salado copper mine’s Alcaparrosa copper mine to a diameter of 36.5 meters and a depth of 64 meters – the height of a 26 meter tall building. . Mines Minister Marcela Hernando assured this week that “there is overexploitation related to the sinking” and that three public bodies will press charges against the mining company.
“Villa Gaby 4 was designed and approved for an exploitation of 400,000 tons, and according to the data obtained during the investigation, it was found that 300,000 tons were mined and there are at least 300,000 more tons in the villa,” said the minister at this Thursday after a meeting with local authorities and representatives of the housing, public works and environment ministries. “This clearly means there is overexploitation that would be related to the sinking, which in turn could have affected the existing aquifer at the site,” he added.
From the mining company Ojos del Salado they have assured that the sinkhole “does not pose any risks to the population since it is 600 meters from the nearest house, while it is more than 800 meters from any other populated center or public service”. es Edwin Hidalgo, manager of external communications and public affairs for the company.
The main concern of the authorities dealing with the matter is the aquifer, which “in the case of mining-related fractures” has led to “water seepage into the mine”, the minister said. Tierra Amarilla Mayor Cristóbal Zuñiga urged technicians to provide urgent answers on the causes that led to the sinkhole “and how to explain that a new circle of cracks is emerging.”
Surface fractures have been discovered in three sectors near the hole, which are monitored by the Chilean National Geological and Mining Service (Sernageomin) using a radar system, drones and extensometers. This Friday they began geophysical studies to confirm that the cracks are not increasing in size.
Ojos del Salado has ruled out that there is any excavation or underground mining going on in the sectors of the rifts and that there are no nearby towns. Hidalgo, a company spokesman, claimed they were discovered before the sinking occurred, “as part of study work in the area and part of an event unrelated to the sinkhole.”
Sernageomin, the Superintendence of the Environment (SMA) and the General Directorate of Waters (DGA) will take legal action against mining company Ojos del Salado over the sinkhole. MPs from the region, for their part, are working on the creation of a commission of inquiry in the lower house.
In the middle of the month, the SMA ordered the mining company six emergency and transitional measures, including conducting a ground stability study in the direct sphere of influence of the event, considering a radius of 500 to 800 meters and providing a technical study to verify that the past water volumes withdrawn by the mining company may or may not have caused disturbance to the alluvial aquifer of the Copiapó River or any other resource in the area. The company has 30 business days to fulfill the orders placed on August 12th.
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