Analysing dynamics of the 2000 Yigong landslide in the Tibetan plateau using seismic observations

Abstract Climate change and urbanisation increase the risk of landslides, particularly mass movements with high mobility that can travel long distances and cause significant casualties and economic losses. Despite their impact, the mechanisms controlling long-runout landslides remain poorly understood due to their complexity. This study investigates the catastrophic 2000 Yigong landslide on the Tibetan plateau, using seismic signals to invert for the force–time function during its movement and evaluate changes in the basal friction coefficient. We identified five distinct stages in the event’s dynamics, beginning with two rock collapses in the source zone during the acceleration phase. In the entrainment phase, the mass attained its maximum velocity and forces when it impacted the Zhamu Creek. Notably, the equivalent friction coefficient dropped from 0.58 to 0.06, indicating a transition from rock collapse to debris flow. Our velocity-friction analysis aligns with flash heating theory, suggesting that high-speed sliding between rough surfaces generated heat, which partially melted the glacier and introduced fluid into the sliding process, resulting in enhanced mobility and facilitated long-runout distances down the Zhamu Creek. This study highlights the value of seismic signals in understanding the physical mechanisms behind catastrophic landslides and addressing the challenges of monitoring these geohazards in remote regions.