The Distribution Pattern of Ground Movement and Co-Seismic Landslides: A Case Study of the 5 September 2022 Luding Earthquake, China

Major earthquakes can cause extensive landsliding that poses a major threat to both property and human lives. In addition to co-seismically triggered ground failure, the earthquake-affected region remains vulnerable to landslides due to loosened and unstable materials and structures. Many researchers have studied landslide distributions and their controlling factors after earthquakes, but the function of ground motion is unclear. To investigate the connection in a strike-slip earthquake, we analyzed the 5 September 2022 Luding earthquake (Mw 6.6) in Sichuan Province, China. We interpreted remote-sensing images to obtain the landslide distribution before and after the earthquake, calculated surface deformation from D-InSAR data (pre- and post-earthquake), utilized a point-source model for the focal mechanism inversion, and then constructed a finite fault model for the rupture slip. There are clear differences in the landslide distributions on the two sides of the fault before and after the earthquake. The density of co-seismic landslides on the west side of the fault exceeded that on the east side. The patterns of surface deformation and ground motion indicated that the areas with larger deformation and motion were associated with more landslides. Furthermore, the landslide size decreased with distance from the fault. A new finding is that co-seismic landslides induced by strike-slip earthquakes result in high landslide concentration on both sides of the fault, while previous studies find that co-seismic landslides triggered by thrust earthquakes present a hanging wall concentrated distribution pattern. These findings contribute to a more comprehensive understanding of the connection between ground movement patterns and landslide distributions. Our research focused on the 5 September 2022 Luding earthquake in Sichuan Province, China. The study identified distinct disparities in the distribution of landslides on either side of the fault, both landslides that happen before, during, and shortly after an earthquake. The western side of the fault exhibited a higher density of landslides following seismic activity compared with the eastern side during the Luding earthquake. The areas experiencing more significant deformation and motion during the earthquake were more prone to landslides. Moreover, landslides induced by strike-slip earthquakes displayed high landslide concentrations on both sides of the fault. In contrast, landslides triggered by thrust earthquakes predominantly exhibited a concentrated hanging wall distribution pattern. The type of fault is a primary controller of the landslide distribution pattern More landslides occurred in areas with more deformation and greater ground motion