## 5 PSI by Means of TSC: Results and Discussion
### PSI Displacement Results  
Figures 13 and 14 show the down-slope ground displacement maps of El Forn de Canillo geocoded over a Google Earth image for the RiskSAR-X and the TerraSAR-X datasets, respectively. For the coherence stability method, a threshold of \(0.65\) has been employed; the PS technique has been carried out using a \(D_{A}\) threshold of \(0.25\); and finally, a threshold of \(0.82\) has been employed for the TSC approach. These thresholds are set in order to ensure the use of pixels with similar phase standard deviations in all cases, as seen in the previous section. Figure 13: Geocoded down-slope linear displacement corresponding to El Forn de Canillo using (**a**) the TSC, (**b**) the coherence stability and (**c**) the \(D_{A}\) approach for the GB-SAR dataset. The black spot indicates the location of the seed employed during the integration step. The white spot indicates the location of the inclinometer S10, which will be employed as ground-truth to validate the results. First of all, notice how the results in the common area processed by both sensors show a high agreement. As expected, the TSC and the coherence stability approaches are retrieving similar deformation trends, except for the increase in pixel density, especially over the land covers characterized by rocks surrounded by vegetation, which may be appreciated at both sides of the landslide. Recall that the ML processing limits the selection of deterministic point-like scatterers surrounded by non-coherent clutter. The denser results benefit the construction of a more robust network during the minimization and integration processes of the CPT, thus improving the reliability of the PSI results. At a more detailed  
Figure 14: Geocoded down-slope linear displacement corresponding to El Forn de Canillo using (**a**) the TSC and (**b**) the coherence stability approach for the TerraSAR-X dataset. The black spot indicates the location of the seed employed during the integration step. The white spot indicates the location of the inclinometer S10, which will be employed as ground-truth to validate the results. level, it must be noticed that the displacement magnitudes obtained by means of the TSC approach reach slightly higher values of displacements compared with the coherence stability results. This difference may be produced by ML carried out during the coherence estimation, which leads to averaging the displacement within the multilooked area. Although the studies reported throughout the paper prevent the employment of the \(D_{A}\) estimator to perform the pixels selection, a PSI processing has been carried out employing the \(D_{A}\) for the GB-SAR study case. Indeed, the displacement results provided by the PS approach clearly result in being unreliable due to the low number of images available (see Figure 13c) and present a large amount of outliers. Regarding the interpretation of the displacement maps retrieved, notice how in the lower part of the landslide, the PSI results obtained show a high agreement with the conclusions extracted from the field monitoring campaigns made between 2007 and 2009 presented in [28] (reviewed in Section 2). The displacement maps obtained reveal that the main body of landslide experienced a residual movement of \(1\)-\(1.5\) cm during the measurements interval. In addition, the local slide of Cal Borro-Cal Ponet may be perfectly identified for both sensors, presenting a higher activity of \(2\)-\(2.5\) cm/year. Finally, some displacement trends, unknown until now, are also revealed in the upper part of the El Forn de Canillo through the TerraSAR-X PSI processing: the crest linking the Pic del Maians to the Pic d'Encampadana and another closer to the area known as Pla del Gespit. These displacements detected exhibit displacements closer to \(\sim\)3 cm/year. Unfortunately, the upper part of El Forn de Canillo lacks instruments to compare and validate the measurements obtained with TerraSAR-X. Despite this, the magnitude of displacement rates suggests that the slope should show activity indicators.