Analysis Of Spatial Distirbution And Susceptibility Evolution Of Co-seismic Landslides Triggered By 2017 Milin Ms 6.9 Earthquake In Tibet,China

At 06:23 on November 18,2017,Ms6.9 earthquake occurred near the Yarlung Zangbo River in Milin County,Linzhi City,Tibet Autonomous Region,where was a sparsely populated area.This earthquake did not cause major casualties and property losses,however triggered a large number of co-seismic landslides,which resulted in blockages in the Yarlung Zangbo River.Few scholars at home and abroad have studied it because the co-seismic landslides of this earthquake were mainly distributed in unmanned areas.This paper would mainly catalogue the co-seismic landslides in detail,and systematically analyze the main characteristics and spatial distribution of co-seismic landslides of this earthquake by using high-resolution satellite images before and after earthquake.According to this results,assessment about co-seismic landslide susceptibility of this earthquake has been made through multiple logistic regression methods and weighted deterministic coefficient method.And the main achivements are as following:1.By comparing the textures,tones and topography of the remote sensing images before and after the earthquake,1818 co-seismic landslides were interpreted in the study area,with a total area of 28.05km~2,the largest single landslide area of2.11km~2 and a landslide impacted area of 500km~2.the co-seismic landslides of this earthquake are mainly rock landslides,which have the characteristics of concentrated distribution and large single scale.2.Seven influencing factors including ground peak acceleration(PGA),elevation,slope,aspect,distance from water system,distance from fault and lithology are selected to study the spatial distribution of landslides caused by the earthquake in Milin,which takes the size and area percentage of landslides in the classification interval as the statistical index.It's could be concluded that the main distribution of coseismic landslides of Milin earthquake is between 30-50°slope,the dominant aspect is southeast and the geological disaster is mainly distributed in deep canyon area.3.Compared with the 2013 Lushan earthquake,the 2017 Ms7.0 magnitude Jiuzhaigou earthquake and the 2018 Ms6.9 magnitude Japan Hokkaido earthquake landslide mobility,the co-seismic landslides of the Milin earthquake are all rocky landslides,which have low mobility.4.To evaluate the co-seismic landslide susceptibility of the Milin earthquake,the multiple logistic regression method and weighted deterministic coefficient method were applied.It's found that the accuracy of co-seismic landslide susceptibility based on the calculation by using data-driven multiple logistic regression method was higher and the 42.0%of the co-seismic landslides were located in high-prone areas.