The mine produces around a thousand tons of copper per day, so any interruption in its operations would have a significant impact.
The accident at Codelco’s El Teniente division, which resulted in the death of one worker, left no injuries but five miners trapped, leading to a complete halt in operations at the world’s largest underground orebody.
According to Chile’s Minister of Mining, Aurora Williams, the incident was classified as “far-reaching,” prompting the issuance of a provisional suspension order for underground operations.
While underground mining inherently involves risks such as rock bursts or collapses, no event with this potential scale of casualties had been recorded in Chile for decades, says Isaac Paredes, Practice Leader at GEM Mining Consulting. In February of this year, a collapse in a mine in Copiapó left three people dead. A larger number of fatalities has not occurred since 1994, when an explosion at the Schwager coal mine claimed 21 lives.
Chile’s worst mining accident also took place at El Teniente in 1945—prior to Codelco’s ownership—where 355 miners tragically lost their lives.
Codelco’s Key Division
Located in the Machalí commune, El Teniente is Codelco’s most productive division. In 2024, it produced 356.4 thousand tonnes of copper, accounting for 25% of the company’s total output, according to Cochilco. In May 2025 alone, El Teniente contributed 30.2 thousand tonnes, representing 23.2% of Codelco’s monthly production.
The search for the five trapped workers remains the state-owned company’s top priority. Regarding the potential duration of the shutdown, Codelco Chairman Máximo Pacheco stated that “the area where the seismic event and accident occurred is a specific section of the orebody. We are fully focused on rescuing those trapped, and only then will we make furtheroperational decisions.”
He also clarified that the concentrator plant, refinery, and smelter at El Teniente continue to operate. “This incident took place inside the mine, in a particular area of the orebody, and therefore, all other facilities remain in operating condition. The affected area does not compromise the rest of the mine,” he noted.
Impact on Production
Experts anticipate that the incident will affect Codelco’s output and finances, with the impact intensifying as the shutdown prolongs. Based on El Teniente’s average output from January 2022 to May 2025, the division produces around 1,000 tonnes of fine copper per day.
“If the suspension lasts for about a week, we could be looking at a shortfall of approximately 7,000 tonnes of copper, which would affect Codelco’s quarterly—and potentially annual—targets,” explains Paredes. The effect could be partially offset by the continued operation of the concentrator and smelter, or by increasing processing rates once activity resumes. Still, he notes, “a temporary production shortfall may be unavoidable.”
Additionally, the accident occurred in a strategic area for El Teniente’s production. “The fact that it happened in Andesit —one of the three currently active underground sectors and a key part of the New Mine Level project—is particularly sensitive, especially given that this sector was about to enter regular production, according to Codelco’s end-of-March reports,” says Juan Carlos Guajardo, Executive Director of Plusmining.
Andesita is expected to contribute a significant portion of El Teniente’s underground output. The incident will likely delay its commissioning, directly impacting operational continuity and the ramp-up of the New Mine Level—critical to extending the mine’s life by another 50 years. “It is reasonable to expect not only production impacts but also effects on operating costs and ramp-up planning,” he adds.
El Teniente’s expected output for 2025 was 336.5 thousand tonnes. Given its weight within Codelco’s overall operations, any prolonged disruption could affect “the achievement of annual targets, the company’s cash flow, and its projected fiscal contribution—though all of this will be subject to technical evaluation once conditions allow,” Guajardo states.
Seismic Challenges
Although the earthquake magnitude—4.2 according to the National Seismological Center—was unusual, seismic activity has long been an issue at El Teniente. “The mine has previously faced microseismic events of magnitude one or two, which are already capable of causing damage,” says Rodrigo Estay, professor at the Department of Mining Engineering at the University of Santiago.
“For some years now, El Teniente has been dealing with a complex situation: the deepening of the orebody. This event will likely prompt several reassessments, particularly regarding seismic safety, as it relates to the seismic activity generated at those depths,” he concludes.
Source: El Mercurio