The disaster near the small town of Brumadinho in southeastern Brazil occurred shortly after midday: on 25 January 2019, at a nearby iron ore mine, the tailings dam – a storage area for the sludgy, fine-grained residues from ore processing, or “tailings” – collapsed. A huge mudslide of around 10 million cubic metres of liquefied tailings flooded the site of the mine, destroying neighbouring settlements and taking a railway bridge with it. At least 270 people were killed. The ecosystem of the Paraopeba River downstream of the mine was ruined. Although the dam had a monitoring system, no one had foreseen the disaster.
The Brumadinho dam collapse resulted in several lawsuits against the Vale mining company and the TÜV Süd inspection organisation. Shortly before the accident, the latter had certified that the dam was sufficiently stable. Vale was ordered to pay the equivalent of around 6 billion euros in damages. An investigation committee concluded that the accident was caused by slowly accumulating microscopic displacements (known as creep) in the deposited tailings layers, but did not provide the exact physical mechanism supporting this hypothesis. In particular, uncertainty remained as to why the dam broke in 2019 specifically – three years after the pond was last loaded with new tailings, and why no significant displacements had been detected prior to the collapse.
Physical mechanism explained
A study by Professor Alexander Puzrin, Head of the Institute of Geotechnical Engineering at ETH Zurich and an expert in landslide modelling, has now shed light on the Brumadinho disaster. The paper appears in the journal external pageCommunications of Earth and Environmentcall_made. The scientists used numerical and analytical models to investigate the causes of the dam failure, and they have identified a physical mechanism that explains the mining accident.