The “5·12” Wenchuan earthquake (2008) induced significant instabilities in rock slopes across faults. Existing studies have focused primarily on static faults or instantaneous seismic effects, yet a quantitative understanding of the dynamic coupling mechanism of energy transfer and slope response (particularly the dip angle effect) during progressive fault dislocation remains to be elucidated. This study utilizes large-scale shaking table model tests on 50° and 30° slopes across reverse faults to systematically investigate the spectral characteristics and energy evolution of slopes subjected to seismic action. Hilbert-Huang transform analysis is employed to analyze the data, with the objective of revealing the cumulative damage mechanism and instability failure pattern. Results indicate that the distribution of seismic energy exhibits a significant hanging wall/footwall effect, with differences more pronounced in the 50° slope than in the 30° slope. Increased dip angles in the hanging wall have been shown to lead to an elevated potential for failure, resulting in rapid localized instability. Fault dislocation has been observed to induce high-frequency responses and energy concentration in slope sections, thereby accelerating crack propagation. It has been demonstrated that steeper fault dip angles promote nonlinear deformation and amplify dynamic responses. Conversely, gentler dips facilitate more uniform energy transmission. Finally, the development of fractures in slopes is determined by the displacement of faults, the shearing forces that result from tectonic activity, and the compression that occurs in the overlying strata. This progression from shallow to deeper regions is a hallmark of seismic activity. The fault dip angle is a critical factor in the control of crack characteristics and the associated instability mechanisms. These findings offer novel perspectives and a scientific basis for the early warning and hazard mitigation of earthquake-induced landslides influenced by fault activity, thereby providing both theoretical and practical significance.