## 5 Discussion
### Insights from Spatial Patterns of Movement Direction and Seasonality  
As mentioned in the previous section, Nair is strongly affected by N-S displacement. This might explain the differing behavior in the correlation analysis related to horizontal displacement, elevation change and direction of movement. Hence, Nair is excluded from further analysis in this section. The tendency towards higher subsidence rates at higher elevations for the lobe shaped rock glaciers at the Grison sites (Figure 7) is in line with previous observations, which showed higher subsidence rates or vertical movement in the root zone of rock glaciers due to plastic deformation [9; 16; 18; 24; 32; 62; 89]. The lack of such a correlation at Kaiserbergtal is probably due to the low elevation range of the main rock glacier body. The decreasing level of elevation change at steeper slopes (Figure 7) indicates that most movement in these areas occurs along the local slope. Surprisingly, no positive correlation between horizontal movement and slopes is observable despite other studies identifying such a link [14; 28; 62; 80]. Most likely, the exclusion of the fastest moving areas due to phase unwrapping errors leads to this effect as these areas show higher slope values during visual inspection than the other rock glacier parts. Moreover, other drivers important for RGV such as ice content, rock glacier thickness as well as the contributing headwall area and the size of the catchment feeding into the landform [14; 80] might superimpose the effect of slope on velocity. Before starting the assessment of the seasonal movement, it has to be highlighted that the observed absolute seasonality does not cover the entire range of the seasonal variability in velocity. Recent studies [19; 20; 23] showed that the seasonal increase in velocity starts with the penetration of melt water into the shear horizons of rock glaciers. This effect of a seasonal increase during snowmelt is not covered by our approach, as the DInSAR time series is not capable of providing information during the melting phase as wet snow leads to a decorrelation of the SAR signal. The here calculated preseason mean movement (\(med_{jint\_jnt}\)) describes the velocity after the increase due to available melt water. As we observe areas with high relative seasonality, which show little to no movement in early snow-free period (June/July) but a systematic increase throughout the summer, we assume that melt water or water availability in general plays a limited role for movement in such areas (Figure 6, Appendix A Figures A2 and A3). Further, the start of movement shows a temporal delay of up to several tens of days after EOS. Hence, not availability of snow melt water but rising ground temperatures might trigger processes in these areas and the temporal delay could indicate when rising surface temperatures start to thaw the frozen subsurface after the insulating snow cover disappeared. Besides, areas with high relative seasonality show little to no horizontal movement and, hence, mostly subsidence (Figure 7). Therefore, we assume that areas with a high relative seasonality might show signs of ongoing permafrost degradation (e.g., Muragl glacier forefield, Gianda Grischa northern rock glacier; Figure 6c,d). The observed process of subsidence might be related to degradation of permafrost due to increasing active layer thickness. We cannot conclude whether the movement observed is reversed during winter due to refereeze and heave, as this process would occur during the snow-covered period with very limited DInSAR observations usable. Besides, the movement rate is most likely below the sensitivity of the 6d interferograms stacking methodology. The spatial distribution of seasonal movement patterns (Figure 6) indicates an increased seasonality towards the upper part of a rock glacier (e.g., Nair, Muragl rock glacier, Davains; Figure 6b,d,e), the root zone, which shows subsidence due to plastic deformation [20,35]. The effect is clearer for rock glaciers with greater lengths (Muragl, Davains).