Chile’s Codelco Halts El Teniente Expansion over Seismic Risk
Mining: Rancagua
Key Facts
—Decision. On 4 August 2026, Codelco temporarily suspended development and construction of the Andes Norte project at its El Teniente mine in central Chile.
—Reason. The state miner cited an emerging deep-seismicity phenomenon at the mine’s lowest levels, which it says behaves differently from risks it has historically managed.
—Scale. The measure affects four contractor companies, more than 20 contracts and about 3,000 workers, according to Chilean media, and pauses a flagship expansion.
—Context. It comes about a year after a fatal collapse at El Teniente on 31 July 2025 that killed six workers; the new step is preventive, with no injuries reported.
—Andes Norte. The sector is the deepest part of the New Mine Level works, at roughly 1,880 metres, holding some 375 million tonnes of copper reserves.
Chile’s state copper giant Codelco has suspended work on the Andes Norte sector of its El Teniente mine after detecting a new deep-seismic risk, pausing a flagship expansion and idling four contractors.
What Codelco Suspended and Why
On Monday 4 August 2026, Corporación Nacional del Cobre (Codelco) said it had temporarily halted development and construction at the Andes Norte project, part of its El Teniente division near Rancagua, about 85 kilometres south of Santiago.
The company described the move as a preventive safety measure taken after identifying an emerging seismic phenomenon at the mine’s greatest depths, with characteristics it said differ from the seismic risks it has historically managed. Recent episodes of deep seismicity, it said, occurred spontaneously and were hard to anticipate.
Codelco said the decision followed technical analyses carried out over the previous six months, and that it would reinforce instrumentation, monitoring and study before defining measures to resume work.
The Contractors and Workers Affected
The suspension directly affects at least four contractor companies engaged in development and construction at Andes Norte, covering more than 20 contracts, according to Diario Financiero.
Chilean outlet Emol reported that roughly 3,000 workers are involved. Codelco said it would carry out an orderly halt covering administrative, contractual and labour matters as it paralyses contractor activity.
Andes Norte is one of the structural projects meant to extend the life of El Teniente, the world’s largest underground copper mine, so a prolonged pause carries implications for Codelco’s long-term output plans.
A Mine Still Marked by the 2025 Collapse
The suspension comes almost exactly a year after a deadly accident at El Teniente. On 31 July 2025, a seismic event triggered a collapse in the mine’s Andesita sector, killing six workers and injuring several others.
Chile’s National Seismological Center measured that 2025 event at magnitude 4.2, while the USGS put it near 5.0. Subsequent expert reviews indicated the tremor was probably induced by mining activity rather than natural tectonic movement.
The 2025 collapse and the 2026 suspension are separate events and should not be conflated: the earlier incident was fatal, while the current measure is precautionary, with no casualties reported. Codelco has framed the new step as acting before, rather than after, a failure.
Why Seismicity Haunts Deep Copper Mining
El Teniente extracts ore at increasing depth, and Andes Norte sits at roughly 1,880 metres, the deepest level of the expansion. As mines go deeper, surrounding rock comes under greater stress, and extraction can release that energy suddenly as rock bursts, or mining-induced earthquakes.
Managing this risk is central to Chilean underground mining, which relies heavily on block-caving methods. Codelco said the newly detected phenomenon behaves differently from the patterns its control systems were built to handle, which is why it chose to stop rather than continue under existing protocols.
What It Means for Codelco and Copper
Codelco is the world’s largest copper producer and a major contributor to Chile’s public finances, so setbacks at its flagship division draw close scrutiny from investors and the government.
The company has been through a difficult stretch: it lost its El Teniente mine manager in August 2025, and three senior executives departed in February 2026 amid internal-audit findings tied to earlier rock-burst incidents. In April 2026, regulators fined Codelco and contractors over the fatal collapse.
El Teniente remains one of Codelco’s biggest divisions, and Andes Norte is central to plans to sustain its output as older ore bodies are depleted, which is why the pause matters beyond the immediate work stoppage.
What Happens Next
Codelco said it will strengthen monitoring, instrumentation and technical analysis before deciding how and when to restart Andes Norte, without giving a firm timeline.
The company stressed that the rest of the El Teniente division and its wider operations continue as normal, limiting the immediate production hit to the paused expansion works.
For the affected contractors and their workers, the coming weeks will hinge on how quickly Codelco can characterise the new seismic risk and design controls that satisfy its safety standards.
Frequently Asked Questions
What did Codelco suspend at El Teniente?
On 4 August 2026 Codelco temporarily halted development and construction at the Andes Norte project, one of the deepest sectors of its El Teniente mine in central Chile, as a preventive safety measure.
Why was Andes Norte suspended?
Codelco cited an emerging deep-seismicity risk detected at the mine’s lowest levels, which it says behaves differently from previously managed seismic patterns. The pause affects four contractors, more than 20 contracts and about 3,000 workers.
Is this the same as the 2025 El Teniente accident?
No. A seismic collapse on 31 July 2025 killed six workers at the Andesita sector. The 2026 suspension is a precautionary pause with no injuries reported, though it stems from the same broader concern about deep-mining seismicity.
Sources
Diario Financiero · Emol · La Tercera · MINING.COM · El Rancagüino
Connected Coverage
Continuing coverage of Chile’s mining sector and Codelco.
Sources: Diario Financiero, Emol, La Tercera, MINING.COM, El Rancagüino.
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