Typical characteristics and causes of giant landslides in the upper reaches of the Yellow River, China

The canyon section from Longyangxia to Liujiaxia in the upper reaches of the Yellow River, which is characterized by a significant number and large scale of landslides, is a typical area prone to landslides. Investigating the characteristics and causes of giant landslides in this region holds great significance for understanding and mitigating the risks associated with such disasters. This paper explored the development characteristics and induced causes of these giant landslides via field surveys, remote sensing interpretations, unmanned aerial vehicle (UAV) surveys, geological dating methods, and numerical simulation methods. There were 22 giant landslides in the study area. Their sliding face is deeply buried in sandy mudstone or sandy stone that is landslide strata and shows large differences in elevation of landslide front and back edges. Most of these landslides mainly occurred tens of thousands of years ago that is indicated by geological dating results. The causes behind these giant landslides have been discussed from various perspectives. Multiple factors, such as tectonic activity, rock properties ("genes"), river erosion dynamics, climate change influences, and ancient earthquakes, are believed to have contributed to the development of giant landslides in this region. Regional tectonic activities exert tectonic forces leading to structural plane formation within rock masses while providing initial conditions for deformation and failure processes associated with giant landslide occurrences. Since the Pleistocene, Yellow River erosion has created favorable spatial environments conducive to giant landslide development by altering slope stress conditions; furthermore, climate change weakens rock mass strength. Finally, earthquakes generate substantial energy serving as catalysts for triggering massive landslide events by inducing rock mass failures.