Use of Interferometric Synthetic Aperture Radar Techniques as a remote tool for Mineral Extraction Sites Monitoring

This work addresses the preliminary achievements of the Horizon Europe European project S34I1 (Secure and Sustainable Supply of Raw Materials for EU Industry) (https://s34i.eu) that aims to increase the autonomy of Europe over raw materials resources through research and development of new data-driven methods devoted to the analysis of Earth observation data. Among the different activities of the project, one of the major contributions is related to the systematic monitoring of mining site instabilities by developing and applying advanced multi- temporal interferometric SAR (InSAR) techniques for the generation of long-term deformation time series. To this purpose, an InSAR multi-grid technique for efficient processing of sequences of differential SAR interferograms (particularly, phase unwrapping operations) has been carried out directly at the native high-resolution spatial grid without any model or assumption on deformation. Experiments were carried out at the Gummern, Austria, extraction site by processing two sets of ascending and descending SAR datasets collected by the EU Copernicus Sentinel-1A/B sensors from October 2014 to March 2023. The line-of-sight (LOS)-projected ground displacement time series were generated by inverting the unwrapped single-look interferograms using the Small BAseline Subset (SBAS) algorithm. Consequently, non-linear and seasonal patterns that could indicate a sudden failure of the surface can be identified with millimetre precision. A post-operation step was also performed over the group of georeferenced common targets as seen from complementary geometries (i.e., ascending and descending orbits) to compute from LOS-projected ground deformations the long-term 2-D (up-down, east-west) ground displacement time series. To this aim, conventional and new combination methods are applied by assuming the north-south displacements do not significantly contribute to the observed LOS measurements.1This study is funded by the European Union under grant agreement no. 101091616, project S34I SECURE AND SUSTAINABLE SUPPLY OF RAW MATERIALS FOR EU INDUSTRY, coordinated by Ana C. Teodoro.