# Potential and Limitations of the New European Ground Motion Service in Landslides at a Local Scale
## 4 Discussion
### La Miera Landslide Characterization  
In relation to the characterization of the spatial distribution and temporal evolution of the La Miera landslide activity, the new EGMS has been successfully applied, since it has been possible to: (1) Monitor the landslide activity between 2015 and 2021; (2) Compare Sentinel-1 A-DInSAR measurements with a building damage inventory [56], detailed geomorphological mapping carried out at 1: 5000, and daily rainfall records. The obtained results are compatible with the building damage and movement evidence observed in the western area of the La Miera landslide and in the El Valle village (Figures 2-5). In the case of the western area of La Miera landslide, the damaged buildings consist of three empty houses built in 1941 [46] with damage categories of 3 and 4 [56] (Figure 5A-C); in the rest of the landslide area, no evidence of movement or damage has been observed (categories <3), although mean velocities detected ranged from \(-\)9.7 to \(-\)4.0 mm/year (Figures 2 and 4). This may be because the velocities detected in the Los Campos and in the La Miera neighborhoods are too low to produce visible evidence in modern dwellings that were built between the 1970s and 2010s [46]. This difference of damage in buildings could be due to difference in construction standards between the structures built in the 1940s and the 1970s-2010s. This landslide, which currently presents different active slope movement typologies, can be classified as an active complex and extremely slow (<16.0 mm/year) landslide, according to the classification of [58]. From the Sentinel-1 A-DInSAR measurements (maximum horizontal motion detected was \(-\)7.9 mm/year) and field evidence (Figure 2, Figure 4, Figure 5, and Figure 7), we can assert that this landslide has a predominantly horizontal component, with a westerly direction and practically no vertical movement. This is consistent with the orientation of the landslide slope, mainly W-E. Moreover, the dip of bedrock layers (Lena Group), which reaches 70\({}^{\circ}\) dip (23), may condition the movement of the landslide (Figure 7). The ascending LOS velocity results do not show significant deformation values while descending LOS velocities present significant active MP. This is consistent with the main orientation of the slope with respect to the ascending and descending orbit geometries (Figure 2). Figure 7 shows a conceptual section from West to East of the La Miera landslide (position is shown in Figure 4), based on topographic, geological, and geomorphological criteria. Since there is no previous work that has defined the thickness of the landslide, the contact between the landslide mass and the bedrock is uncertain. A-DInSAR measurements are also shown. B1 is the location where damage to categories 3-4 was observed (Figure 7). The geomorphological mapping at scale 1: 5000 carried out during this research has made it possible to validate and check the Sentinel-1 A-DInSAR measurements. Thus, Sentinel-1 A-DInSAR measurements, geomorphological evidence, and building damage reveal both active and stable areas. In the case of El Valle village, four buildings built before the 1950s [46] have presented a damage category of 3 [56] (Figure 5D,E). The damage observed is compatible with active ground motion, who's maximum VLOS and horizontal velocity detected were \(-11.6\) and \(-7.2\) mm/year. Therefore, this would demonstrate a spatial correlation between geomorphological evidence, building damage, and EGMS data. Previous studies demonstrate the influence of meteorological factors, particularly daily rainfall, on landslide activity evolution. Thus, rainfall causes acceleration once pore-water pressures have increased to sufficient levels in the landslide body and deceleration occurs when the pore-water pressures drop [59]; this is caused by groundwater level changes in the landslide body due to rainfall [60]. Therefore, landslides can slow down or stop moving during dry periods and reactivate or fail catastrophically during wet periods [61].