## 6 Conclusions  
Evaluation of tailings dam stability is a complex geotechnical study, involving the hydrogeological settings assessment, the analysis of the tailing material composition, the deposition technology and the possible triggering factors leading to dam failure, like man-made factors but also including earthquakes or heavy rainfalls. The monitoring of these delicate and important infrastructures is of strategic importance to prevent damage or failures and to plan tailored risk mitigation measures. Satellite remote sensing technologies, such as satellite SAR Interferometry, represent a consolidate and effective tool for monitoring of structures and infrastructures, including the tailings dams, allowing for analysis of the whole basin, and obtainment of temporal information, using data archives. The deformation processes at Zelazny Most tailings dam have been analyzed by A-DInSAR technique from October 2014 to April 2019, showing that the storage facility is affected by both vertical deformation (settlements or compaction phenomena) and horizontal sliding towards the outside of the dam. The displacements have been compared with the deformation pattern observed by in situ measurements for the previous years by [PERSON] [1], especially for the eastern part of the dam. Subsidence or settlements in the tailings dam constructed by the upstream method, where the new embankments are founded on tailings, is generally expected as its height increases. The settlement rates of the 2014-2019 period is lower than those described by [PERSON] [1] for the previous years, but they have a constant growth trend during the analyzed period. The more affected zones are the upper and the recent parts of the TSF due to both a lower consolidation degree of the recent tailings, and a larger thickness of compressible materials in this inner part of the dam structure. Horizontal displacements at the Zelazny Most TSF are of primary importance in assessing the stability of the dam. The direction of such horizontal displacements is radial from the center of the dam basin, and in the eastern and northern sectors, it is more severe in some localized areas, while the western sector is moving westward evenly. The outward displacements can be produced by two combined factors: the load of the tailings is pushing the dam forward along horizontal slip zones at depth in the glaco-tectonic surfaces located in the over consolidated Pliocene clay, where the shear strength is close to the residual. This mechanism could end with a passive failure in front of the dam, with a major negative impact on the economy, surrounding properties, and people's lives aggravated by possible large run-out distances. An accurate monitoring of the storage facility is therefore of crucial importance, especially in the dam sectors where intense deformations have been identified. A proper monitoring plan to mitigate the risk of a dam failure could include the use of Terrestrial SAR interferometry ([54; 55; 56]), which is considered a proper technology for early warning purposes. Due to its high sampling frequency of data collection (in the order of few minutes or even seconds) and its high accuracy of displacement measurement (up to decimal millimeter order), this technique can be effective for high resolution, local-scale real-time monitoring. A subsequent development and improvement of this study should consist of the accurate estimate of the local displacement field, including possible N-S movements, overcoming the intrinsic limitations of the 1-D LOS measurements of the satellite SAR interferometry [48; 49]. A straightforward approach is the combination of multiple InSAR LOS measurements from different viewing geometries and different angles of incidence [57; 50], but it is also possible to resolve the full 3-D surface displacement vectors merging LOS measurements together with other geodetic observations, mainly GPS data [58; 59; 60]. Conceptualization P.M., B.A., A.S., F.B.