Deadly Collapse at Chile's Largest Copper Mine Linked to Mining Activity

Last month, a seismic event caused a fatal collapse at Codelco's El Teniente, one of the world's biggest underground copper mines located in Chile. According to a person with direct knowledge, the incident was likely caused by geological stresses resulting from the mine's own extraction processes, rather than any naturally occurring shifting of tectonic plates.

The 4.2-magnitude tremor affected a newly developed area of the mine, known as Andesita, killing six workers and injuring nine others. While Codelco had initially reported the damage to be around 700 meters of tunnel, the Public Prosecutor's Office has now stated that 3,700 meters (over 12,000 feet) of tunnel were affected, including in the Recursos Norte area that has been producing for more than five years.

The scenario that Codelco is leaning toward is one shared by many industry experts, who believe the seismic activity was more likely the result of mining than from natural causes. The panel-caving method used at El Teniente routinely involves the controlled collapse of depleted areas, which, combined with simultaneous mining in other areas, could have increased stress within the ore-body, leading to the sudden release of stored energy.

As Codelco seeks to restart operations in unaffected areas, the company faces a major question of whether it is safe to resume underground mining at El Teniente, which accounts for a quarter of its copper output. A one-day suspension could bring a loss of about 750 tons of copper, or roughly $7.5 million in revenues.