## 4 Results and Analysis  
### Analysis of InSAR Deformation Results  
Figure 4 shows the spatial-temporal baseline distribution, which was generated according to the small baseline principle described in Section 3.2. This paper limited the temporal baseline to 5-36 days to keep high coherence of interferograms. The Sentinel-1 satellite exhibits high orbit control accuracy, with its orbit tube diameter being significantly smaller than the critical spatial baseline. Therefore, we did not constrain its spatial baseline. Before the disaster, 240 interferograms were created from ascending track 12 and 220 from descending track 48; after the disaster, 39 interferograms came from descending track 48. The mean deformation rates and time-series deformation of South Lhonak Lake were measured via line-of-sight (LOS), as depicted in Figure 5a,b. The positive values indicate displacement towards the satellite, while negative values indicate movement away; blue signifies positive displacements while red shows negative. The underlying image is a GF-2 optical image taken on 26 December 2020. Figure 3: The primary workflow of GPU-assisted full-resolution InSAR fast time-series analysis. The figure is adapted from [PERSON] et al. [19]. The InSAR analysis has revealed the presence of two distinct zones of deformation within the moraine encircling South Lhonak Lake. A significant deformation zone, which is positioned in the northern sector of the moraine, displayed persistent deformation patterns well in advance of the catastrophic event. This area exhibited a gradual and sustained subsidence along with localized ground displacements, indicating a protracted period of instability. Figure 5a illustrates that the maximum deformation rate derived from the ascending images is about \(-80\) mm/yr, whereas the overall deformation rate from the descending images is slightly lower (Figure 5b), with a maximum deformation rate of around \(-65\) mm/yr. The significant deformation area results from both ascending and descending images generally align with the landslide area observed through optical images. In the deformation results from the ascending images, the area with the highest mean deformation rate is within the landslide area, while a portion of the area with the highest mean deformation rate from the descending images lies to the east of the landslide area. Figure 4: Spatial and temporal baseline configuration of Sentinel-1 datasets. (**a**) Ascending (Track 12) images prior to the disaster; (**b**) descending (Track 48) images prior to the disaster; (**c**) descending (Track 48) images after the disaster. The significant deformation area from the ascending images is more congruent with the landslide area. To further analyze the deformation area of the landslide, four points (P1 to P4) were selected and shown in Figure 5. The time-series deformation curves for these points, obtained from the ascending and descending images, are presented in Figure 6a,b, respectively. It is evident that the overall deformation trend of the selected points from both ascending and descending orbits indicates relatively small deformation signals before January 2022, with relatively flat curves. However, starting from 2022, the deformation rate markedly increased. The inflection point indicating acceleration in the ascending images is around January 2022. Deformation results derived from the ascending images reveal that the deformation rate is higher than the descending rate. Figure 5: The average LOS deformation rate of the surface surrounding South Lhonak Lake before the disaster. The dashed red line delineates the landslide area, and points P1–P4 were selected for further analysis of the time-series deformation within this area before the GLOF. (**a**) Derived from ascending (Track 12) images. (**b**) Derived from descending (Track 48) images. mation on the eastern side of the landslide area is most pronounced, with a deformation rate exceeding \(-60\) mm/yr.