A thunder at the beginning of the 21st century-The giant Yigong Landslide

摘要

On April 9,2000,a huge landslide occurred in Yigong of Tibet,China,drawn world wideattention because it has revealed a large extent of geological process of gravitational erosion in a very short timeand brought heavy economic loss and ecology disaster. Afterwards,many professional researchers have been thereto investigate the landslide and over 40 technical papers published. In this paper,a method of RS+GIS combiningwith site survey was used to interpreate the landslide features and characteristics of each part of the ZhamunongGorge where the landslide occurred. Based on the investigation results,the location,shape and dimensions of thepre-sliding mass were determined,and it is demonstrated that this landslide has flied through a 3700 m long nar-row canyon at high speed. It has found much evidence of the high-speed sliding mass crashing the left slope of thegorge mouth,being disintegrated and forming high-speed debris-flow. The deposit structures of the debris flowand the size of each part of the deposit were obtained in this paper. Based on the previous study results,it is con-sidered that the Yigong Landslide is a type of high-speed landslide-debris-flow. The motion model of this kind oflandslide was established based on its movement characteristics. By comparison of the structure of landslide andpre-sliding mass with the dimension of the landslide-debris-flow deposit,it is calculated that the Yigong Landslideis 3150 meter high with a volume of 91.1×106 m3,which is slightly different from the previous estimations.