Identifying potential debris flow hazards after the 2022 Mw 6.8 Luding earthquake in southwestern China.

Earthquakes can generate large amounts of co-seismic landslide debris and unstable hillslopes, which supply abundant material sources for subsequent debris flow activities, leading to a significant increase in debris flow risk in post-seismic years. On 5 September 2022, a Mw 6.8 earthquake struck Luding County in the mountainous region of Southwestern China. To mitigate the risk of post-earthquake debris flows to infrastructure and reconstruction planning efforts in the earthquake-affected area, it is crucial to determine the location and magnitude of post-earthquake debris flow. Based on the dataset of debris flow activities for more than 10 years after the 2008 Wenchuan earthquake, we captured the dominant factors controlling the post-earthquake debris flow activity and developed a predictive model for the post-earthquake debris flow activity by multiple machine learning methods. Subsequently, we used the predictive model and transfer learning method to identify high-susceptibility areas for debris flows following the 2022 Luding earthquake. A volume indicator of transportable material sources (PVL) by coupling with the connectivity and the co-seismic landslide was proposed to further quantify the magnitude of debris flows. The results indicate that approximately 70% of the catchments in the Luding earthquake-affected area would remain at a slight or low debris flow activity level, while the catchments with high and very high activity are mainly located in the Moxi-Xinmin section. Overall, this research provides valuable insights for mitigating the risk of post-earthquake debris flow and developing effective strategies for reconstruction efforts. [ABSTRACT FROM AUTHOR]