Emergency rapid assessment of landslides induced by the Luding MS6.8 earthquake in Sichuan of China

Abstract

Seismic landslides can seriously aggravate the losses of earthquake disasters. Therefore, it is of great significance to assessment the distribution of earthquake induced landslides for emergency relief. In this paper, based on the 30 m resolution DEM and regional geologic data with a scale of 1∶500 000, emergency rapid assessment of earthquake induced landslides is carried out using the Newmark cumulative displacement model for the 5 September 2022 Luding MS6.8 earthquake, China. The results show that the earthquake induced landslides are relatively serious in this earthquake. The high hazard zones of the coseismic landslides are about 45 km2, which is mainly distributed on the two banks of the nearly east-west tributaries on the west bank of the Dadu River and the west of the Xianshuihe fault, especially along the Yanzigou, Mozigou, Hailuogou, Feishuigou gullies and the Wandong, Shiyue, Tianwan rivers, posing a great threat to the lives of residents and tourists. The rivers and roads in these tributaries are at high risk of being blocked by landslides. The Lengqi, Xinglong, Moxi and Detuo towns in Luding County and Tianwan, Caoke, Xinmin, Xianfeng, Xieluo and Wajiao towns in Shimian County are at high risk of landslides. The S434 Provincial Road and S211 Provincial Road along the Dadu River near the epicenter are more likely to be blocked by landslides. The predicted earthquake landslide hazard in the Gongga Snow Mountain area is medium, but it is necessary to pay attention to the risks of long range and high position landslide disaster (chain), such as ice avalanche and rock avalanche. Comparison between the distribution of induced landslides in zones with intensity VIII and IX obtained from post-earthquake emergency investigation and remote sensing interpretation shows that the obtained displacements can well reflect the macro distribution of coseismic landslides along the tributaries on the west bank of the Dadu River, but cannot be exerted effectively around the edge of the Moxi platform and the banks of the main stream of Dadu River, which can be enhanced through the improvement of large scale of geologic maps and high quality topography data. The results can provide reference for valuable timely reference information on post-earthquake reconstruction planning and long-time activity of post-earthquake geohazard and risk recognition of landslide disaster chains.

Keywords

• luding earthquake
• seismic landslide hazard
• emergency rapid assessment
• newmark displacement model