On 25th January 2019, the tailings dam of the Brumadinho iron mine in Minas Gerais, Brazil failed. The mud slide that this caused resulted in a death toll of 259 with 11 people missing as of January 2020.
Radar images from the Sentinel-1 satellite mission, which had been regularly gathering data for at least two years prior to the collapse, have been processed to show the capability of Terra Motions unique APSIS© InSAR method in assessing the likely causes of the collapse and as to whether the collapse could have been predicted.
The APSIS© surveys have been independently analysed by researchers at the University of Nottingham and Durham University and the results published in Nature Communications Earth & Environment. Their conclusions were as follows:
In contrast to attempts using other InSAR techniques, the ISBAS (now part of APSIS©) method detected evidence of anomalous deformation on the dam wall and beach which was not consistent with consolidation.
An analysis of these accelerations using inverse velocities enabled correct predictions of the time interval for the collapse of the dam.
The unique capability to be able to survey the entire dam structure, something not possible using other InSAR methods, was the clear advantage here. Furthermore, APSIS© surveys do not need any ground surveys to be in place – only the satellite data is needed. This makes it ideal as the basis for a low cost monitoring system that can be used by mine operators and regulators alike.
Figure taken from the paper showing the inverse velocity analysis (left) for four deforming areas across the dam (right).