Monitoring pre- and post-failure InSAR-derived deformation in surface mining complexes

• Pre- and post-failure deformation is compared in surface mining complexes. • InSAR observations reveal precursory deformation months to years before failures. • Post-failure deformation hotspots persist or even exceed pre-failure velocities. • Ongoing post-failure deformation may indicate residual instability. Operations in surface mining complexes are frequently associated with geotechnical engineering instability, which can have serious consequences for mining operations, nearby communities and the environment. Monitoring surface deformation is therefore a critical component of safe mining practices, and satellite-based Interferometric Synthetic Aperture Radar (InSAR) has become a widely used tool for this purpose. While most studies have focused on the conditions leading up to failures, post-failure deformation processes remain poorly investigated, even after events involving fatalities. In this study, we analysed ten cases in surface mining complexes worldwide, involving slope failures in open pits, tailings dams, heap leaches and waste dumps, six of which involved fatalities. Using InSAR, we examined surface deformation during both the pre- and post-failure periods, not only in the area specifically affected by the failure but also across the entire mining site, aiming to determine whether surface deformation anomalies diminish following such failures within the mining complex as a whole. Our results show that all failure sites exhibited precursory movements months to years before the events. Furthermore, we identified post-failure deformation hotspots across several mining areas, with some exhibiting velocities exceeding those prior to failure at the initial failure sites. These findings highlight the persistence and spatial redistribution of deformation within mining complexes following failure events, underscoring the importance of continued deformation monitoring beyond the immediate failure zones.