## 4 Results
### Dynamic Feature Monitoring of Glacier Movement Based on Sentinel-1
#### 4.2.3 Postseismic  
Based on POT technology, this article presents the average deformation rate four months after the Luding M\({}_{5}\) 6.8 earthquake (Figure 7). As shown in Figure 7, there are also large-scale glaciers still moving along the track after the earthquake. The epicenter of the Luding earthquake was near Hailuogou Glacier No. 1, close to three large modern glaciers on the eastern slope of Mt. Gongga (less than 10 km in a straight line from both Hailuogou and Mozigou Glaciers and less than 20 km from the ice tongue of Yanzigou Glacier). The glaciers and periglacial areas more actively affected by the earthquake were concentrated in the central and southern parts of the main peak. The accumulation area of Hailuogou Glacier No. 1, the trailing edge of Hailuogou Glacier No. 2, the upper reaches of Mozigou Glacier, and the main peak of Mt. Gongga were affected by the Luting earthquake with drastic displacement changes. The maximum flow velocities in the positive and negative LOS directions were 3.3 and \(-\)0.9 m/d, higher than the average velocities before the earthquake. The average postseismic velocity in three areas of Hailuogou Glacier No. 1 in the firm basin reached 2.5 m/d and that in local areas could reach 3 m/d. The flow velocity at the junction between the upper edge of the ice waterfall and the firm basin could reach 2 m/d, twice the average flow velocity before the earthquake.  
Figure 6: The POT deformation results. (**a**) Sentinel-1A SAR images between 26 August and 7 September 2022; (**b**–**d**) LT-1 SAR image coseismic surface displacements between 4 September and 12 September 2022.  
To further investigate the effects of the earthquake on the morphology of some of the glaciers in the study area, four selected points were chose at different locations, including Mozigou Glacier, Hailuogou Glacier, and the main peak of Mt. Gongga (see Figure 7; P1, P2, P3, and P4), to carry out postseismic displacement time-series analysis in the study area. Figure 8 shows the time-series evolution for points P1-P4 in the LOS direction, with each point recording the cumulative shape variables four months after the earthquake. The ground deformation at each selected point in the time series based on the cumulative deformation variables showed a gradual increase in the post-earthquake monitoring period. Of these four points, P3 had the largest cumulative deformation of about 73 m. The overall movement trend for the displacement of the four points initially showed an increase in velocity and then a slow increase in surface displacement with time. In addition, there were no visible glacier dynamics anomalies from the temporal displacements of each sample during the selected data collection period, neither in the accumulation zone nor in the ablation zone.  
Figure 8: Time-series results for the surface displacement field of the selected sample points.  
Figure 7: (**a**) The POT deformation results from Sentinel-1A SAR images between 7 September 2022 and 5 January 2023; (**b**) localized surface velocity of Yanzigou Glacier; (**c**) localized surface velocity of Mozigou Glacier; (**d**) localized surface velocity of Hailuogou Glacier No. 1.