On the afternoon of 31 July 2025, a collapse occurred in the Andesita sector, part of the expansion project of Codelco’s El Teniente underground copper mine, as a consequence of a seismic event of magnitude 4.2, recorded some 36 km northeast of Rancagua and at approximately 500 metres depth.

The incident resulted in the deaths of six contract workers (one from the company Salfa Montajes and five from Gardilcic), as well as nine injured.

The Public Prosecutor’s Office ordered the closure of the mine and launched an investigation to determine responsibility, considering whether the tremor had natural causes or was induced by mining activities. Sources who requested anonymity stated that the accident was due to the mining activity itself.

The companies were invited to comment on the allegations. Codelco’s response is available, but Gardilcic and Salfa Montajes did not reply.