Dynamic processes of the Dora Kamiyama rockslide in the Tibetan Plateau, China: geomorphic implication

The mechanisms of high-speed and long-runout landslides are reflected in the geomorphology of their deposits. Comprehensive field investigation using unmanned aerial vehicles photography was undertaken to observe special landforms of the Dora Kamiyama rockslide in the Tibetan Plateau. The dynamic processes of the rockslide were analysed based on the complex topography that remained. The age of sediments sampled from the landslide lake was tested through optically stimulated luminescence (OSL). In translation zone II, the landslide material near both edges underwent sinistral or dextral shearing motions, forming levees. In accumulation subzones III-1 and III-2, a rapid extensional sliding process contributed to toreva block formation. Transverse and longitudinal ridges developed due to compression-dominated processes in subzone III-2. Meanwhile, high-speed material was overturned in subzone III-3 due to the original topographical resistance, and carapace facies featuring abundant megablocks were clearly visible on the surface. Ridges confined by troughs were well-developed across the area experiencing rapid radial spreading motion in subzone III-4. Finally, dynamic parameters of the rockslide were calculated. The equivalent friction coefficient and the angle of reach were 0.40 and 21.80°, respectively. The maximum sliding velocity was estimated between 37.42 and 54.73 m/s. The OSL ages showed that the occurrence time of the rockslide can be estimated to be 4.24 ± 0.35 ka, defining it as an ancient landslide in the Holocene.