A huge circular crater, 32 meters wide and 64 meters deep, formed in the middle of a road crossing land owned by a mining company.
A week later, the hole expanded: now its diameter 36.5 metersaccording to the latest satellite measurements.
The Chilean National Service for Geology and Mining (Sernageomin) ordered the mining corporation Compañía Candelaria to paralyze all of its operations in the area.
He also initiated the process of sanctions against the company, while the team investigates the possible reasons for the failure.
How did
Geologists interviewed by BBC Mundo explained that there could be several natural phenomena or human activities that cause this type of sinkhole.
But basically they consider two: the first will be related to heavy rains falls in the area in July.
“You have multiple layers in the ground, and there are multiple ways that water can break down,” said Chilean geophysicist Cristian Farias, director of civil works and geology at the Catholic University of Temuco.
He explained that “when a lot of rainwater falls on soil with high levels of gypsum, the water seeps through and erodes the entire lower section in a matter of days, making the upper section less stable and eventually causing collapse.”
The second hypothesis points to mining impact in the zone.
Candelaria develops a copper deposit in Tierra Amarilla, and the adits of its mine go into the bowels, both in the vicinity of the well and below it to a much greater depth.
NOW: Parallel to work inside the mine #caperrosean internal operational committee is being activated along with mining and geology specialists to update information and analyze the next steps in the investigation of subsidence in #YellowEarth pic.twitter.com/yrJZz3860F
— Sernageomin (@Sernageomin) August 6, 2022
“Preliminary information available points to the intervention of a mining company that has been overexploiting minerals in the area,” said Cristobal Muñoz, director of the information NGO Red Geocientífica de Chile.
Munoz pointed out that the company “was supposed to mine 38,000 tons of ore, but formerHe brought about 138,000 tonsmore than three times” in this field.
He pointed out that mining interference could destabilize the soil by diverting groundwater from its natural course and emptying aquifers, creating spaces that encourage the earth to sag and fall under its own weight, forming a sinkhole.
Compañía Candelaria, for its part, acknowledges the overexploitation of minerals, but insists that it was completely legal.
“In regards to the over-extraction, this was reported to the authorities by the company itself,” said Edwin Hidalgo, the company’s public relations manager.
A source in the sector explained to BBC Mundo that copper miners typically produce more material than budgeted due to detonation of explosives, among other things.
The representative of the corporation objected that it was premature to draw conclusions, and stressed that “various events are being investigated that could cause a failure, among which the showers recorded in July are especially relevant.”
Residents of Tierra Amarilla staged a protest on Sunday, and its mayor, Cristobal Zúñiga, asked the mining company to take over, though he didn’t point it out, pending the outcome of the investigation.
Mining Minister of Chile Marcela Hernando promised go “to the last consequences” punish those responsible as soon as they are identified.
how much more will it grow
Landslides on the walls of the funnel have been constant in recent days, up to an increase in its diameter by 450 cm to the current 36.5 meters.
“At first it began to expand at the bottom; then an asymmetric shape began to be created, and what is on top has no support, so it starts to fall and slowly but sharply expands until it reaches the shape of a cylinder, ”said Farias, author of Volcanoes and Earthquakes.
Thus, it is predicted that it will continue to grow, at least until the diameter at the surface equals the diameter at the bottom, i.e. 48 meters.
Munoz, for his part, believes it could even grow if new destabilizing factors emerge on the ground.
“In any case, it could not be more than 200 or 300 meters, which is important for us, because nearest town is 600 meters away”, he stated.
And he did not rule out that this phenomenon is replicated in other areas of the region.
“Areas that would be more susceptible to the occurrence of other funnels are also being studied,” he said.
In fact, there is a precedent in Tierra del Fuego: in November 2013, after the collapse of the underground structure of the mine, a funnel 20 meters long and 30 meters wide and 30 meters deep was formed.
why is it round
He also drew attention to the fact that the crater forms almost perfect circle.
“The rounded appearance of such a hole is due to the shape of the collapse,” said Christian Farias.
The geophysicist explained that a landslide “starts at a point and spreads symmetrically, that is, in all directions, radially, and this causes everything that collapses to do it in a circle and at some point stops when it becomes stable.
“Many collapsing structures in nature happen this way. When volcanoes collapse, for example, because the volcanic building collapses under its own weight, or there were fluids that are no longer there, the resulting structure is usually very round; sometimes a little more oval, but more often round.”
What will happen to the hole
It also remains to be seen what the future holds for the unexpected failure of Tierra Amarilla. Will it be closed or left out in the open?
“The volumetric capacity of this funnel is quite large. To be honest, it’s not easy to fill it, so the solution would be secure this perimeter and put up security barriers,” said the director of the Geoscience Network of Chile.
It is important for Muñoz to “make sure people don’t go there to take pictures” as accidents can happen.
And he also emphasized that even if it was to fill it up, it might be in vain because of the very nature of the hole.
“You have to think that the part of the earth that has fallen is no longer down there, because there is a liquid there, which is water. When he fell, he walked like a river.
The mining company’s public relations manager, for his part, assured that most of the sediment had accumulated at the bottom of the pit, reducing its depth from 64 meters to 62 meters, according to his latest measurements.
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Source: La Opinion
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