## 2 Methodology  
In this study, we used IPTA Multi-baseline (IPTA-MB) and SBAS approaches implemented through the commercial GAMMA(r) and SARScape(r) software, respectively. The main differences between the two methods concern the rationale (step-by-step for IPTA or semi-automatic for SBAS) and the data format. Regarding products, the output of the two methods are equivalent, and there are no significative differences in the quality and accuracy of the derived deformation maps. According to the product provider expertise, one of the two approaches can be exploited. In the IPTA approach, the temporal and spatial characteristics of SAR point targets are exploited to retrieve the mean surface deformation velocities and the related time series of displacement [21]. The advantages and the benefits of the proposed technique are: (a) the step-by-step rationale that allows the user to accurately check and refine any processing step; (b) the use of point scatter targets to reduce geometrical decorrelation; (c) the potential to find scatterers in low coherence areas, thus filling the gaps in deformation maps and then resolving both high phase gradients and phase jumps; (d) the use of vector format data structures instead of the raster data format (typically used in conventional interferometry) that allows drastically reducing the disk space required for data storage; and (e) the possibility of obtaining deformation information, even though a reduced number of images is available. The main processing steps of the GAMMA software package to implement the IPTA-MB technique are summarized below (Figure 1): (a) assembling a stack of co-registered single-look complex (SLC) images with the related SLC and orbit parameters; (b) selecting a candidate list of point targets (plist) based on coherence and/or amplitude mean-to-sigma ratio thresholds; (c) selecting the interferometric maximum spatial and temporal baselines; (d) obtaining an initial estimate of interferometric parameters (e.g., deformation, topography, atmosphere, noise); (e) identifying the iterative improvement of different parameters based on the results of previous steps; and (f) finally, the provision of multi-temporal InSAR results, e.g., deformation maps and time series together with height and quality information by solving the system of deformations equations through the singular values decomposition (SVD) method. Further details about the IPTA technique can be found in [PERSON] et al. (2018). The SBAS approach is a multi-temporal InSAR approach that provides the mean velocity and time series of surface velocities at medium (about 80 \(\times\) 80m) and full (about 10 \(\times\) 10 m) spatial resolution ([PERSON] et al., 2018), depending on the adopted multi-look factors and native resolution of the SAR system. It preserves the full area coverage ensured by actual spaceborne SAR systems despite a coarse spatial resolution. The proposed technique provides a stack of InSAR pairs starting from coupled SAR images acquired along nearby orbits (small spatial baselines) with low revisit time (small temporal baselines), by setting the allowed maxima spatial/temporal baselines. This enables minimizing the spatial and temporal decorrelation issues affecting the InSAR pairs, and increasing the spatial density of the point measurements of deformation. Also, it aims at mitigating atmospheric artifacts and topographic or orbital errors by applying spatial/temporal filtering. The expected outputs are characterized by high measurement accuracy for both mean velocity (about 1-2 mm/year) and surface deformation (about 5 mm).