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Objective The shallow potential sliding layer of a slope is an important feature in seismic geological disasters. Its characteristics, such as slope shape and slope structure, tend to complicate the dynamic response and slope damage. Methods In this paper, the landslide in Xinhua Village, triggered by the Lushan Ms 6.1 earthquake, is taken as a case study, and two-dimensional discrete element computational models are developed based on a field investigation. The dynamic response and simulate instability are investigated by comparing numerical simulations of homogeneous and heterogeneous models, representing pure terrain and a shallow potential sliding layer, respectively. Results The findings are as follows: (1) The potential sliding layer at the shallow surface of the slope exhibits significant dynamic amplification, which typically increases nonlinearly with height; (2)The slope surface shape has an obvious influence on the slope amplification effect.In the convex part, the amplification effect of the horizontal and vertical acceleration of the slope surface is significant, while the amplification effect of the concave part is lower than that of the convex part; (3) In the Xinhua Village landslide, the convex terrain is destroyed before the concave terrain under the effect of micromorphology, and its instability process is divided into five stages, namely, local seismic cracking of vibration amplification, convex terrain destruction, concave terrain destruction, complete destruction of the overall slide and gravity accumulation. Conclusion The research results are helpful for deepening the understanding of potential unstable slopes induced by earthquakes and shedding light on disaster prevention and mitigation.

The Beishan area in Tianshui City is located in the transition zone between the mountainous area on the northern edge of the Qinling Mountains and the Loess Plateau. The solid internal and external dynamic coupling has induced large landslide groups with a zonal distribution, which seriously restricts urban planning and disaster risk prevention in Tianshui City. Based on the systematic summary of existing geological hazard data, this study used the space-sky-earth integrated survey method to identify the variations of loess thickness from west to east, typical slope structure types, and key slip-controlling strata. The seismic landslides' development characteristics, distribution rules, and geometric and kinematic features are systematically analyzed. The results show that the landslide groups in the Beishan area are concentrated along the north bank of the Jihe Valley in a zonal distribution. The landslide types are mainly mudstone landslide and loess-mudstone interface landslide, with multi-stage rotation, translation, and multi-stage sliding. The stratigraphic structure consists of the overlying Quaternary loess and the underlying lacustrine-fluvial mudstone and claystone of the Neoproterozoic Yaodian and Ganquan formations. The landslides belonging to the bedding rock slope have three typical slope structures from west to east. The loess thickness increases gradually from west to east, the elevation and apparent friction angle are lower in the east and west and higher in the middle, and the scarp height of the landslides is higher in the east and west and lower in the middle. In addition, the seismic landslides in this region have long-runout characteristics. The equivalent friction coefficients of these landslides are between 0.21 and 0.28, and the seismic landslides in the eastern and western sections have stronger movement.

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