Regional seismic slope assessment improvements considering slope aspect and vertical ground motion

Seismic slope stability assessments in active fault zones are very important prior to designing and constructing large engineering structures. However, in most previous regional-scale analyses, ground motion records are either used directly or replaced by empirical regression equations. In this paper, we present an improved regional seismic slope stability assessment method considering the vertical slope aspect and ground motion. Based on limit equilibrium models and finite element models, best fit equations are obtained to calculate the sliding angle and factor of safety (FOS). Then, a two-stage integration process is applied to obtain the permanent displacement. The new model has been tested in the Chenghai active fault zone, China, under a seismic precautionary intensity of 9, and the results of the new model are compared with those of traditional infinite slope models. The results show that ignoring the vertical ground motion and slope aspect leads to underestimation of co-seismic landslide hazards on regional scales, and the new model provides a more accurate index to evaluate co-seismic slope behaviours in large areas. •A more accurate model considers the vertical ground motion and slope aspect.•New regression equations to calculate sliding angle and FOS are generated.•The ignorance of these two factors underrates the co-seismic landslide hazard.•The dominant sliding direction is determined by two horizontal ground motions.