## 3 Results
### Potential Application for Structural Monitoring  
The procedure described in Section 2.3.2 has allowed to identify all the couples of PSs respecting the criteria to be combined. The velocity components \(V_{V}\) and \(V_{EW}\) have been estimated for each couple, by implementing Equation (1) presented in Section 2.1. In Figures 11-13, the maps of \(V_{V}\) and \(V_{EW}\) are shown. The symbology has graduated colors ranging from dark red (downwards and west-directed displacements, respectively) to dark blue (upwards and East-directed displacements, respectively). The green points are representative of stable areas, not affected by displacements. Figure 11: Area no. 1: mean velocity vertical component \(V_{V}\) (**a**) and mean velocity East-West component \(V_{EW}\) (**b**) for the combinable pairs of PSs. Figure 12: Area no. 2: mean velocity vertical component \(V_{V}\) (**a**) and mean velocity East-West component \(V_{EW}\) (**b**) for the combinable pairs of PSs. Synthetic maps have been created from the previous ones, showing for each cluster the significative values of the velocity components. In Figures 14a, 15a and 16a, for the Areas 1, 2 and 3, respectively, the following information is graphically represented: \(V_{V,max}\) and \(V_{V,min}\), with a star marker, placed in their current position; \(V_{V,mean}\) with a circular marker, placed in the middle of the cluster; the values of \(V_{V,mean}\pm 1\sigma\), with triangular markers, on the two sides of \(V_{V,mean}\). Analogous maps are represented for the EW components of velocity, in Figures 14b, 15b and 16b. Figure 14: Summary maps for Area \(1\): graphical representation of the meaningful values of the mean velocity vertical components \(V_{V}\) (**a**) and of the mean velocity East-West components \(V_{EW}\) (**b**), for each cluster. Figure 13: Area no. 3: mean velocity vertical component \(V_{V}\) (**a**) and mean velocity East-West component \(V_{EW}\) (**b**) for the combinable pairs of PSs. In Area 1, an ongoing deformation phenomenon can be observed (Figure 14). In particular, the vertical component is prevailing, showing downward movements. The vertical velocity increases from the top left zone to the bottom right zone. Differential displacements can also be observed in the same building. It is even more evident looking at the summary maps. For example, the last building of the third \"row\" has a \(V_{V,min}\) value in the yellow range ([\(-0.3\)--\(-0.1\)] cm/y) and a \(V_{V,max}\) one in the orange range ([\(-0.3\)--\(-0.5\)] cm/y). In the EW direction, the velocity maps show lower velocity values. Moreover, in Area 2, an even clearer ongoing deformation phenomenon can be observed (Figure 15). The vertical component is the prevailing one, with downward movements, but the EW component is not negligible in some buildings. The buildings most affected by the vertical deformation phenomenon are those of the southern zone, that reach values of \(V_{V}\) also lower than \(-0.7\) cm/y. Significant displacements can also be observed  
Figure 16: Summary maps for Area 3: graphical representation of the meaningful values of the mean velocity vertical components \(V_{V}\) (**a**) and of the mean velocity East-West components \(V_{EW}\) (**b**), for each cluster. Figure 15: Summary maps for Area 2: graphical representation of the meaningful values of the mean velocity vertical components \(V_{V}\) (**a**) and of the mean velocity East-West components \(V_{EW}\) (**b**), for each cluster. on some buildings. For example, in the second building on the right, starting from the bottom, the vertical component increases from north to south, while, on the contrary, the EW component decreases from north to south. It is even more evident looking at the summary maps. The examined building, in fact, presents a \(V_{V,min}\) value within the green range ([\(-\)0.1\(\rightarrow\)0.1] cm/y) on the North-East side, and a \(V_{V,max}\) one in the dark red range ([\(<\)\(-\)0.7] cm/y) on the south side.