The Role of Slope Orientation and Source Mechanism in Topographic Amplification: Insights from the 2022 Ms6.8 Luding Earthquake

We utilized the source process inverted from near-field strong-motion records and three-dimensional spectral element method to simulate the strong ground motion of the 2022 Mₛ6.8 Luding Earthquake, analyzing frequency-dependent topographic amplification and resonance effects with particular emphasis on the influence of slope orientation relative to seismic wave propagation direction on ground motion amplification.Key findings reveal a strong correlation between landslide intensity and vector peak ground velocity (VPGV), with the most severe slope failures occurring in areas characterized by the highest VPGV values. In critical zones, the maximum PGV components aligned with the slope dip direction, likely enhancing downslope driving forces and triggering failures, while significant vertical ground motion served as an additional triggering mechanism.Slope orientation relative to seismic wave propagation fundamentally controlled energy distribution patterns. Wave-facing slopes exhibited significant amplification due to geometric focusing effects and scattered wave interference, while opposing slopes showed attenuation through suppressed direct wave amplitudes. Micro-scale topographic features displayed contrasting amplification patterns, with localized wave-facing zones within opposing slopes showing stronger amplification primarily driven by direct body waves, and wave-opposing zones within facing slopes functioning as seismic energy barriers through geometric defocusing and destructive interference. The strike-slip mechanism governed both topographic amplification and scattered wave generation, with the tangential component dominating horizontal motion and amplification.