Frequent seismic activity in the Yigong region of Tibet poses a serious threat to slope stability. This study investigates the Yigong rock mass using field surveys and discrete element numerical simulations to systematically reveal the critical role of repeated seismic loading in triggering the massive 2000 Yigong landslide. The results demonstrate a three-stage progressive failure mode under seismic conditions: the initial damage phase is characterized by the expansion and connection of rear-edge fractures; the stable deformation phase features accelerated development of secondary joint networks; and the final instability phase involves overall structural collapse accompanied by significant block rotation and ejection. Frequent earthquakes lead to rock mass fragmentation and strength degradation, which are identified as key factors in inducing this extremely large landslide. The findings clarify the mechanical mechanisms of progressive failure in rock slopes within high-intensity seismic zones, providing important theoretical and practical support for early identification and risk management of geological hazards in southeastern Tibet.
Wang et al. (Mon,) studied this question.