## 3 SAR Datasets and Methodology
### Coherent Pixels Technique  
The algorithm used for processing satellite radar images is the \"Coherent Pixels Technique\" (CPT), developed by [PERSON] et al. [41] and then implemented by [PERSON] et al. [42] with Temporal Phase Coherence (TPC) at the Remote Sensing Laboratory (RSLab) of the Universitat Politecnica de Catalunya (UPC). This algorithm allows the development of the entire interferometric chain using image pairs with reduced spatial and temporal baselines, thus characterized by a better phase response. The CPT-TPC is a robust algorithm that effectively processes satellite radar images to show surface deformations. Its unique capability to work with image pairs characterized by reduced spatial and temporal baselines results in a better phase response, which is crucial for obtaining accurate information about such deformations. Additionally, CPT-TPC is known for its robustness against atmospheric disturbances and decorrelation noise, making it a reliable choice for this study. One of the strengths of CPT-TPC is its ability to select radar targets (RTs) that exhibit good electromagnetic response stability. RTs are reflectors materializing as existing ground elements, such as manufactured structures (buildings, monuments, roads, railways, pylons) or natural elements (rock outcrops). Therefore, they generally cannot be found in areas characterized by widespread vegetation. Analogous to geodetic networks, the set of RTs identified in an area under investigation can be considered a dense natural network of measurement points whose positions and movement velocities are referred to as fixed points, assumed as stable over time, having recorded determined coherence values. During processing, the velocity of these reference points is conventionally set equal to zero. By focusing on these stable reflectors, the algorithm reduces the impact of errors and noise in the final output, thus enhancing the results' accuracy.  
The processing procedure consists of three main phases:  
1. Generation of the best interferograms from the available image dataset.
2. The selection of RTs characterized by a fixed phase value is considered indicative of good electromagnetic response stability;
3. Calculate average displacement velocities and the temporal displacement series of the selected points in the considered observation period.  
The output results obtained from CPT-TPC processing are generally characterized by a high degree of precision and accuracy intrinsic to the algorithm.  
The precision of the measurements indicates the degree of convergence of the measured values around their mean, while accuracy quantifies the distance between the measurements and the actual data. Regarding interferometric data, issues related to precision and accuracy involve the georeferencing of reflectors, the determination of the mean displacement rate, and the determination of the time series of displacement. Concerning the spatial positioning of reflectors, the conversion from SAR coordinates to UTM-WGS84 (here Z33N) coordinates is affected by a positioning error in the North-South and East-West directions, equal to \(\pm\)5 m. The presence of disturbances, such as atmospheric and decorrelation noise, results in error in the velocity measurement of the order of \(\pm\)5 mm/year. The error related to the ellipsoidal height of each point is estimated at \(\pm\)1.5 m.