Abstract: The northern continental slope of the South China Sea is a large-scale submarine slope that extends in a belt-like configuration from the southeastern waters of Hainan Island to the southwestern waters of Taiwan Island. Several canyons and numerous steep slopes are located at this area. Due to the complex geological structure and earthquake-prone nature of the area, various geo-hazards such as landslides are active. In particular, due to the large topographic relief and frequently seismic activity, earthquake-induced landslides often occur in the region. So it is important to scientifically assess the seismic stability of large submarine landslides. In this study, a three-dimensional numerical model was developed using Scoops3D and GIS technology to investigate the seismic stability of typical steep slope groups located at canyons in the northern continental slope of the South China Sea. The results show that ：Most of the canyon profiles in the study area are in the shape of “U”, and it is inferred that the canyons are type Ⅱ submarine canyon system. Strong seismic action can substantially weaken the stability of submarine slopes located at canyons, in which the regional minimum safety factors of steep slope groups in C1 canyon dramatically decreases to 0.50 while the horizontal seismic coefficient with the increase to 0.40. The seismic-induced destabilization range of the steep slope groups in the western canyon is significantly higher than that in the eastern region, and most of the landslides are concentrated in the valley walls on both sides near the crests of the peaks, while a considerable portion of the landslides are located at the eastern valley walls of the southern section in C1 and C2 canyons, with the overall distribution being a belt-like shape. 

Key words:  , northern continental slope of South China Sea, submarine landslide, 3D slope model, seismic stability, steep slope groups in canyon area