Abstract Identifying the optimal intensity measures (IMs) of ground motion is a critical step in the seismic fragility analysis of slopes using probabilistic seismic demand models. In this study, we investigated various IMs of earthquake ground motions, considering both vertical and horizontal components that can trigger landslides, through numerical simulations. A set of 19 IMs was examined for three heights of slopes. The optimal IMs were assessed using the maximum permanent displacement as an engineering demand parameter. The findings reveal that acceleration-related parameters specifically sustained maximum acceleration (SMA) and root-mean-square of acceleration, and velocity-related parameters namely sustained maximum velocity (SMV) and peak ground velocity, are the most effective IMs for slopes subjected to both vertical and horizontal ground motions. For slopes subjected exclusively to horizontal ground motion, SMA is recommended as the optimal IM for lower-height slopes, while SMV is more suitable for the taller slope. In contrast, for models subjected to combined horizontal and vertical ground motions, SMA is consistently identified as the optimal IM for slope across all heights. Notably, the study concludes that peak ground acceleration, a commonly used parameter in seismic analysis, is unsuitable for the considered slopes.
Tran et al. (2026) studied this question.