## 4 Results  
The A-DInSAR velocity maps of the Zelazny Most TSF, for the period October 2014-April 2019, are shown in Figure 4. The panels a and b show the LOS velocity, in ascending and descending orbital geometry respectively, while c and d the east-west and up-down velocity maps, respectively. For the LOS velocity maps, the used convention for the color bar is as follows: green PSs represent the velocity range between \(-\)2.5 and 2.5 mm/yr, which has been considered no deformation; PSs moving away from the satellite are in yellow, orange, and red, while PSs moving toward the satellite are from cyan to blue. For the east-west and up-down velocity maps, the green PSs represent no displacement; yellow to red PSs are moving westwards or downward, respectively, while cyan to blue PSs are moving eastward or upwards, respectively. As regards the horizontal displacements (east-west direction in Figure 4c), it is worth noting that, along the eastern embankment of the dam, PSs are moving eastwards with velocity up to 30 mm/yr, while along the western embankment, PSs are moving westwards, with similar maximum rate of displacement (up to \(-\)30 mm/yr). Therefore, in these sectors of the dam, the embankment is deforming outwards, i.e., the velocity vectors are radial with respect to the center of the basin. Along the northern sector of the dam, instead, the east-west deformation rates are very small, with values ranging between 5 and \(-\)5 mm/yr. The horizontal rates in the north-south direction, as mentioned in the previous paragraph, cannot be properly measured by InSAR [49; 50]. As regards the vertical displacements (Figure 4d), PSs moving downwards (subsidence) are in yellow to red colors, while there are no areas with PSs moving upwards (uplift). The velocity values measured along the vertical direction show that several parts of the dam ring are affected by subsidence or settlement (hereinafter considered as synonyms). The southern part of the dam shows lower subsidence (from \(-\)5 to \(-\)15 mm/yr), while in all other sectors of the dam, subsidence is more intense, especially in the innermost and higher rings. In the eastern sector, the subsidence rate is up to \(-\)30 mm/yr in the innermost part of the tailings dam ring, with peak values of \(-\)50 mm/yr in the central part of the eastern sector. Subsidence decreases up to values of \(-\)5 mm/yr towards the base of the dam structure, i.e., in the so-called starter dam. In the western sector of the tailings dam a similar pattern of deformation can be observed: in the innermost rings the subsidence is up to \(-\)30 mm/yr, while in the starter dam the settlements are in the order of \(-\)6 mm/yr. In the northern sector of the dam, the maximum velocity is about \(-\)35 mm/yr in the inner portion of the dam and decreases in the starter dam. In order to analyze the trend of horizontal and vertical displacement over time, the time series of displacement has been computed for each measurement point. Some interesting examples are shown in Figure 5: for each sector of the dam, four time series selected at different highs of the dam body are represented (location of the selected points is also given in the map panels). For each dam sector, Points P1 are located near the beach and the ponds, in a higher position; points P2 and P3 are selected in the middle highs, and P4 are located on the starter dam. The time series of vertical displacements (Figure 5a) highlights that the points P1 show steep trends, as they are affected by intense deformation. The deformation pattern increases quite steadily over time (from October 2014 to April 2019), with a linear trend. The displacements become more and more moderate, going down in altitude at points P2, P3, and P4 (less steep time series).