Search

A good understanding of giant landslide-prone areas could greatly enhance the understanding of the formation and failure mechanisms of giant landslides. In this study, a classic giant landslide-prone area named the Diexi area located along the upstream stretch of the Minjiang River on the eastern Tibetan Plateau is adopted to analyze the failure mechanism and evolution process by detailed field investigations, Unmanned Aerial Vehicle (UAV) images and a digital surface model (DSM). The results show that among the 37 giant landslides located in the Diexi area, 18 landslides are transverse landslides (wedge failure), and the others are consequent landslides (buckling failure). All landslides blocked rivers, and some barrier lakes still remain. The Diexi area features special geological structural conditions related to the hinge section of the Jiaochang arc tectonic belt, the intersection of two active fault zones (the Songpinggou and Minjiang fault zones) and high levels of geostress. The numerous radial fissures induced by the Jiaochang arcuate belt provided lateral sliding boundaries for buckling deformation (consequent landslides) and head scarps for wedge failure (transverse landslides). The rapid incision (1.88 mm/yr) since the middle Pleistocene formed a deep gorge with steep slopes and strong lateral unloading. Frequent earthquakes and rainfall further reduced the rock mass integrity, and strong earthquakes or other factors triggered the landslides. [ABSTRACT FROM AUTHOR]