Probabilistic Seismic Landslide Hazard Assessment Considering Different Scenarios of Earthquake and Rainfalls in Bomi, China

Abstract. Probabilistic seismic landslide hazard assessments are critical to infrastructure safety and disaster mitigation in earthquake-prone zones. Previous studies on the probabilistic seismic landslide hazard (PSLH) assessment considered only earthquakes, while rainfall was rarely or not yet considered, which might affect significantly the spatio-temporal pattern of potential seismic landslides. Considering the uncertain features of both earthquake and rainfalls, we developed a novel method for PSLH assessment referring to static factors (geology, topography, and landuse/landcover) and dynamic factors (earthquake and rainfalls), and assessed the PSLH in Bomi, China, which is a strong earthquake-prone zone threatened by heavy rainfalls in the southeast of the Tibet plateau. Firstly, the earthquake parameters under four kinds of earthquake scenarios, being frequent, occasional, rare, and extremely rare, were obtained with the probabilistic seismic hazard analysis method to quantify the effect of future earthquakes. Secondly, we quantified the spatio-temporal distribution of the soil slope saturation with a rainfall infiltration model considering the monthly different rainfalls. Then, considering the different scenarios of both earthquake and rainfall, we assessed in detail the PSLH with a permanent displacement model. The results show that the risky zones of seismic landslide hazards differ significantly in Bomi under different scenarios, where high and extremely high hazard zones concentrate mainly in the south part; and the pattern of seismic landslide hazards changes a lot with monthly differential rainfalls. The method presented in this study is meaningful for the prevention and mitigation of seismic landslides in other mountainous areas threatened by strong earthquakes and suffering from heavy rainfalls.