Characteristics and susceptibility assessment of the earthquake-triggered landslides in moderate-minor earthquake prone areas at southern margin of Sichuan Basin, China

This paper aims to characterize the EQ (earthquake)-triggered landslides and to assess the EQ-triggered landslide susceptibility in moderate-minor earthquake prone areas at the southern margin of Sichuan Basin, China. 284 EQ-triggered landslides were inventoried from field-based investigation and dominated by rockfall, soil slide, and rock avalanche. Statistical analyses show that the volume of EQ-triggered landslides ranges from 20 to 1,510,000 m3 with concentrations in the range of 20–10,000 m3, corresponding to 90% of the total amount of landslides. Among these EQ-triggered landslides, 38.4% occurred in the areas seriously affected by the mining in terms of causing factors and 89.8% occurred in the carbonate rock distribution areas lithologically. The geological conditions with widely developed karst and goaf amplified the influence of moderate-minor earthquakes. 14 key conditioning factors are selected to construct landslide susceptibility map by weighted information value method (E-IV), weighted certainty factor method (E-CF), and support vector machine (SVM) methods. The results show that the AUC values of E-IV, E-CF, and SVM are 0.867, 0.857, and 0.884, respectively, indicating three methods present good prediction accuracy, while the SVM has the highest accuracy. Landslides mostly clustered in the coal mining and carbonate rock area, which are widely affected by karstification (dissolution void or fissures) and goaf. Meanwhile, the very high landslide susceptibility areas are mainly distributed in the Gongchang Anticline tectonic area with 652 km2 from the best SVM method. This study can provide insights into EQ-triggered landslides in frequent moderate-minor EQ-impacted regions.