Exploitation of InSAR techniques as a support of in situ sensors to improve safety and productivity in mining operations

The Brumadinho dam disaster occurred on 25 January 2019 when a tailings dam at the Corrego do Feijao iron ore mine in Brazil suffered a catastrophic failure of devastating consequences over hundreds of kilometres with a severe toll on the environment and the population. The collapse of Brumadinho tailings dam could be considered among the worst incidences related to mining operations in recent years. Unfortunately, it will not be the last tragedy of this kind. According to researchers at World Mine Tailings Failures, the risk of occurrence for these catastrophic events will increase in the near future. Mining operations are typically monitored by employing sparse networks of in situ sensors (prisms, ground-based radars, piezometers, etc.). This information does not cover the totality of the possible areas affected by deformation. Furthermore, it is difficult to manage since it is obtained from different sources, whose integration and comparison become a complex task. In this context, spaceborne synthetic aperture radar (SAR) interferometry (InSAR) technology represents an attractive alternative to complement the monitoring of mining operations due to its capabilities. On the one hand, spaceborne InSAR could provide measurements of terrain deformation with millimetric precision over wide areas. And on the other hand, the monitoring can be carried out regardless of day-night cycles or the weather conditions in the areas of interest. In recent years, the InSAR technology has improved, allowing the exploitation of key indicators revealing precursors in the trend of deformation time-series. This paper takes Cadia and Brumadinho as test sites and shows the potential of cross-sections and inverse velocity analysis to complement in situ sensors for the rapid identification of critical deformations on tailing dams and slopes in open pits. Finally, an example of an online platform is presented as a way of improving the user experience to exploit InSAR monitoring services jointly with in situ information over a map of reference. This provides the end-users with a single platform with all the monitoring data to make easier the spatio-temporal analysis of the deformation and the assessment of critical spots of deformation.