第八届青年地学论坛

On 05 September 2022, an Ms 6.8 (Mw 6.6) earthquake occurred in Luding County, Sichuan Province, China, with an epicenter at 29.59°N, 102.08°E and a focal depth of approximately 16.0 km. Combining field investigations, high-resolution satellite images and multiple datatypes characterizing the seismogenic structure, topography and geology, this study attempts to discuss the influence of geomorphic and tectonic indexes on landslide distribution. The results show that the 2022 Luding earthquake, whose seismogenic fault is the Moxi fault, was a sinistral strike-slip event that triggered at least 4528 landslides over an area of ~2000 km². These landslides span a total area of 28.1 km², and the western section of the seismogenic fault, which serves as the active wall area, is characterized by a higher landslide concentration, especially in the Wandong Basin. The seismogenic fault and lithology influence the regional distribution of landslides, and more landslides occurred closer to the seismogenic fault and in the controlling lithologies of granite and dolomite. Local topography influences the landslide occurrence position on the slope; the eastern section is prone to form landslides in the lower gorge section, and the western section is prone to form landslides in the upper-top section of the gorge. For coseismic landslides in the eastern Baryan Har block, the eastern boundary (Longmenshan fault), whose earthquakes are characterized by thrust with slight dextral strike-slip movement, could be the primary landslide-prone area; the southern boundary (Moxi fault; southern segment of Xianshuihe fault), with more intensive strike-slip movement, may be the secondary landside-prone area; and the northern boundary is the tertiary landside-prone area. Additionally, the current landslide inventory may be underestimated, although this underestimation has limited influence on the results.
 

Landslides,Luding earthquake,Spatial distribution,Geomorphic index,Tectonic index