"Original features of Vale’s tailings dam may have been responsible for failure – study", 17 January 2024

...New research out of ETH Zurich suggests that certain features of the tailings dam at Vale’s Corrego do Feijao iron ore mine in Brumadinho, southeastern Brazil, may have been the cause of the burst that released 10 million cubic metres of liquefied tailings, destroyed neighbouring settlements, took a railway bridge with it and killed at least 270 people.

In a paper published in the journal Communications of Earth and Environment...explains...[:]...[I]ts earth dam was raised several times by a few metres, as is customary in ore mining...

According to the new findings, some initial slip surfaces had already appeared at the height of the second step as the dam was being built. With the progress of construction, these slip surfaces increased in length but remained too short to cause a collapse. However, after the tailings dam was decommissioned in 2016, these surfaces continued to expand horizontally and eventually reached a critical length. As a result, the layers of tailings began to move, causing the dam to burst under their weight...

In Puzrin’s view, the findings are worrying in two respects: the slip surface that caused the disaster apparently grew at a time when the pond was no longer being loaded with new tailings...and the growth of the slip surface did not lead to any significant external deformation of the dam that the monitoring system could have recognized as alarming...