Nearly a year after a rock burst killed six contract workers and injured nine others at the El Teniente underground copper mine, in the O’Higgins Region, 90 kms south of Santiago, a damning 122-page investigation by Chile’s National Geology and Mining Service (Sernageomin) has concluded that the deaths were not the result of an unforeseeable natural event, but of systematic management failures, ignored warnings and a deliberate decision by the chain of command to keep workers in areas known to be dangerously unstable.
The report, finalized in May 2026 and obtained by Chilean media in June, lays bare a pattern of corporate negligence that extended from the mine floor to the highest levels of the state-owned copper giant. Its findings confirm what workers decried from the beginning, that management had foreknowledge of the dangers, but kept them working.
On July 31, 2025, at 5:34 p.m., a rock burst measuring 4.3 Mw—equivalent to approximately 4.7 on the Richter scale—tore through two sections of El Teniente, the largest copper mine in the world, accounting for more than a quarter of the Chilean National Copper Corporation’s total production. The energy released, estimated at 6.9 × 10⁹ joules, caused massive structural collapse.
At the maintenance workshop in the Andesita sector, a 24-cubic-meter wedge of rock, weighing roughly 60 tons, broke from the ceiling and buried Paulo Enrique Marín Tapia, a 48-year-old worker from contractor Salfa Montajes Industriales, who was drilling holes for pipe anchor bolts. He was found dead by rescue teams.
At the intersection of Socavón Hw and Loop 1 in the neighboring Recursos Norte sector, the rock mass collapsed entirely, destroying the existing support system and producing a ceiling uplift of up to 20 meters. Five workers from contractor Constructora Gardilcic, Gonzalo Ignacio Núñez Caroca (33), Alex Araya Acevedo (29), Carlos Andrés Arancibia Valenzuela (34), Jean Humberto Miranda Ibaceta (31) and Moisés Esteban Pavez Armijo (33), were waiting for a scissor-lift vehicle to begin their shift. They were struck by the massive rock projection and killed instantly.
All six dead were subcontracted workers, a fact that speaks of the two-tier system that defines modern mining where the most dangerous work is outsourced to contractors whose wages and conditions are substandard.
The warnings
The Sernageomin report establishes that the mine’s own seismic monitoring system, known as the Criterion of Event Frequency (CFE/CFT), which tracks whether seismic activity is within a normal band, had been flashing red for days.
Between July 26 and 28 and on July 30, the indicator fell below the normal band. On the morning of July 31, just hours before the disaster, operational reports noted “high seismicity” in the Dacita Sur, Recursos Norte, and Reno sectors. At approximately 2:00 p.m. on the day of the accident, workers on their lunch break reported hearing a blast “much stronger than the usual blasting” and of unusual intensity.
None of these warnings triggered any protective action. Management ordered that operations continue in the exposed sectors. The shift supervisor, operating under a procedure known as P-03, had the authority to note that seismicity was “out of range” while simultaneously declaring that operations would continue without “restriction.”
The report states explicitly: “The chain of command deliberately chose to ignore danger thresholds, validating the entry of contractor personnel into sectors that, based on technical data available in real time, should have been immediately evacuated. This decision constitutes a grave breach of the duty of care by the principal employer.”
Procedure P-03 is El Teniente’s governing document for work in the Transition Zone, the area of highest geo-mechanical risk between the caving zone and undisturbed rock.
After a major seismic event on July 24, 2023 in which a ceiling collapse at the exact same Loop 1 intersection, left a 13-meter over-excavation—a gaping wound in the rock mass that fundamentally altered the geometry and stress distribution of the tunnel, Sernageomin formally and urgently ordered Codelco to comprehensively update P-03. Two years later, at the time of the July 2025 disaster, no update had been made.
Moreover, the procedure delegated the decision to evacuate entirely to shift supervisors, with no mandatory escalation mechanism to geomechanics specialists or safety management.
After the 2023 event, Codelco repaired the sector with a standard support system: bolts, mesh, shotcrete and cables. The Sernageomin report finds that this was a “local, static repair without reengineering for the dynamic response of the rock mass to higher-magnitude events, whose probability of occurrence had already been flagged.”
Critically, the 13-meter over-excavation was never addressed with higher capacity structural support of steel frames, fill pillars, or equivalent measures. Nor was the area permanently closed to personnel. Instead, pedestrian and equipment transit continued through what the report describes as a zone that “should have been permanently sealed.”
The report also notes that a geological fault running northeast-southwest, an alignment known to be structurally unfavorable under the existing stress regime, which paralleled the Loop 1 tunnel. This was in the geological data available to Codelco and was not incorporated into operational controls.
One of the report’s most significant findings concerns the structural design of the mine itself. When Sernageomin approved the Recursos Norte project in 2018, it did so on the explicit condition that a 120-meter-wide “decoupling pillar” of solid rock would be maintained between Recursos Norte and the adjacent Reservas Norte and Dacita mining sectors. This pillar was the primary structural barrier designed to prevent the propagation of geomechanical stresses between mining zones.
In 2021, Codelco obtained approval to expand Reservas Norte and in doing so, mined out the very pillar that the 2018 approval had designated as a safety barrier. No formal re-evaluation of the Recursos Norte geomechanical assumptions was conducted. The operation continued under conditions radically different from those originally approved, without the regulator being informed of the implications.
The report concludes that this “transformed a theoretically safe design into a high-risk configuration for the propagation of cascade damage.”
Codelco blames the regulator
A La Tercera/ Pulso June 12 article reported that Codelco had filed an administrative appeal (recurso de reposición), as a formal response to Sernageomin’s findings. It is remarkable for its audacity. The company makes three arguments:
Firstly, it claims the report imposed “obligations with fatal deadlines” without giving Codelco the opportunity to exercise its right of defense, a procedural objection that ignores the year-long investigation during which Codelco had every opportunity to present evidence.
Secondly, it argues the report “suffers from a methodological bias.” The company contends that observing severe damage from a 4.3 Mw event and concluding that control measures were insufficient is a flawed syllogism: “The insufficiency of a measure to contain a given event does not demonstrate that the measure was inadequate when it was designed and implemented. It demonstrates, at most, that the event exceeded the parameters for which it was designed.”
This is the logic of the insurance adjuster, not the safety engineer. It amounts to saying: the roof fell because the earthquake was bigger than we planned for, not because we planned inadequately. But the whole point of safety margins in mining engineering is precisely to account for events that exceed normal parameters. A support system that works only under conditions that do not threaten it is no support system at all.
Thirdly, and most cynically, Codelco argues that “the operational conditions and control measures had been previously inspected by the competent authority” and that operations had been authorized to resume after the 2023 event. In other words, Sernageomin approved what they are now condemning. This defense conveniently omits that Sernageomin’s post-2023 approvals were based on information that Codelco has admitted was incomplete.
The political context: From Boric to Kast
The disaster occurred in the final months of Gabriel Boric’s presidency, as his Approve Dignity coalition was heading toward electoral defeat. Boric rushed to Rancagua to lead the rescue operation, promising that “all responsibility must be assigned,” a promise that rang hollow from a president whose labor minister and chosen successor, Communist Party member Jeannette Jara, had spent her tenure enforcing the very subcontracting regime that made the disaster possible.
The Codelco board chairman under Boric, Máximo Pacheco, initially attributed the rock burst to natural tectonic activity, a claim the Sernageomin report now definitively refutes. Pacheco commissioned an “international audit” whose terms of reference were designed from the outset to treat the deaths of six workers as a matter of administrative fine-tuning rather than criminal culpability.
Now, under the government of José Antonio Kast, the political calculus has shifted. Kast’s newly installed Codelco board chairman, Bernardo Fontaine Talavera, made El Teniente the symbolic center of his accession. His first field visit, on June 4, 2026, was to the mine. “I wanted my first field visit to be to El Teniente because this is an emblematic operation for Codelco and for Chile,” Fontaine declared. “This division has had to face one of the most complex periods in its recent history. Here we experienced a tragedy that reminded us that safety can never be taken for granted.”
Fontaine created a dedicated El Teniente Safety Committee within the board and declared that “our mandate is not to produce for the sake of producing, but to do so safely, efficiently, and profitably.” The emphasis on “efficiently and profitably” is the operative clause. The Kast government has used the accumulated crises of the Boric era as the defining indictment of state management of Codelco, preparing the ideological ground for what comes next.
The Kast government’s program of tax cuts for corporations and the wealthy, combined with its tax stability guarantees for foreign investors, creates the fiscal and legal architecture for the privatization of what remains of Chile’s state-owned copper industry. The narrative is already being assembled: Codelco, under state management, concealed safety data, got workers killed, and inflated its production figures. The solution, the argument will run, is to bring in “professional” management, private capital and market discipline.
The El Teniente disaster was not caused by state ownership. It was caused by the relentless pressure to cut costs, outsource labor and maximize production that is inherent to the capitalist mode of production that operates whether the owner is a state corporation or a private shareholder. The subcontracting regime that put six contract workers in harm’s way is the same regime that prevails at BHP’s Escondida, at Anglo American’s Los Bronces, and at every other mine in Chile. Codelco outsources more than 70 percent of its workforce to contractors. At the private transnationals, the figure is closer to 80 percent.
The Sernageomin report documents, in exhaustive technical detail, what happens when the drive for profit is given priority over human life. Each decision was made by managers under pressure to maintain production, keep costs down and to avoid the disruption that a shutdown would entail.
What remains is the political question: will the working class draw the necessary conclusions?
The answer cannot be to exchange one set of capitalist managers for another. The answer is to place the mines under the democratic control of the workers themselves, as part of a planned economy organized to meet human needs rather than to generate private profit. The international unity of the working class, across the divisions of contractor and direct employee, Chilean and foreign-born, is the only force capable of ensuring that no more workers are buried alive in the pursuit of copper.
(Sources: Sernageomin, Informe de Investigación de Accidente Fatal, Codelco Chile División El Teniente, May 2026; WSWS, “Tunnel collapse kills 6, leaves 9 injured at Chile’s El Teniente copper mine,” August 10, 2025; La Tercera / Pulso, June 12, 2026.)