基于确定性系数方法的龙门山地区地震滑坡影响因子敏感性分析——以汶川地震与芦山地震诱发滑坡为例

在我国西南地区，沿龙门山断裂带分别发生了2008年汶川M_S8.0级地震以及2013年芦山M_S7.0级地震，这两次地震均造成了严重的地表破裂，并诱发了大量的滑坡和崩塌等次生地质灾害。文章选择了位于青藏高原向四川盆地过渡的区域——以龙门山断裂带为中心的30°~34°N，102°~106°E区域作为研究区，借助GIS工具，基于确定性系数（CF）方法，选取了地震、地质构造、自然环境和人类活动4大类因子，包括烈度、震中距、岩性、断裂、高程、坡度、坡向、河流、降雨、公路共10个因子（子集），对汶川和芦山地震诱发的次生滑坡灾害进行影响因子敏感性分析，基于z值确定该区域内地震滑坡的关键因子类以及基于CF值确定各类集（子集）下各特定因子的具体地震滑坡敏感性。研究结果显示：地震因子具有最高的z值，是龙门山地区地震滑坡产生的关键影响因子，表明地震活动的强弱直接关系到斜坡的稳定性和次生滑坡灾害的面积分布。而对比烈度子集中的具体CF值表明：当烈度小于Ⅷ度时，烈度对次生滑坡发生的影响极低，区域内的主要影响因子则由地震因子转变为震中距、自然因子等其他类别的因子；其次以坡度、高程、与河流的距离为主的自然因子类别以及与断层的距离在地震滑坡过程中也有较高权重，而人类活动对研究区内坡体的稳定性也有着不可忽略的作用。本研究结果可作为该地区后续区域地震滑坡相关研究和发展规划的基础科学依据。

Susceptibility analysis on factors of co-seismic landslides in the Longmenshan area based on the certainty factor method-Case study of the Wenchuan and Lushan earthquake-induced landslides

In Southwest China, the 2008 Wenchuan MS8.0 earthquake and the 2013 Lushan MS7.0 earthquake occurred respectively along the Longmenshan Fault zone system, both of which produced serious surface ruptures and caused a large number of secondary geological hazards, such as landslides and collapses in a broad region with the area of over 1100 km2. In this paper, the transition area from the Tibetan Plateau to Sichuan Basin is selected as the research area, which is in the region of 30°~34°N, 102°~106°E, with the Longmenshan fault system being central developed. Ten cities, such as Chengdu, Ya'an and Mianyang, and so on, are involved in the research region, covering the distribution area of all landslides induced by these two earthquakes. The study area is located at the upper stream region of the Minjiang River, Tuojiang River, Fujiang River and the Jialingjiang River, which is affected not only by the East Asian monsoon and the Indian Ocean monsoon, but also by the circulation system of the Tibetan Plateau because of the special geographical location and climatic conditions. The stratigraphic lithology of the study area is complex, mainly composed of the deposits of the Quaternary lakes and modern rivers, mudstones, shale and soft rock mass. Among them, the soft rock mass is represented by relatively broken magmatic rock mass damaged by weathering, rain water erosion and fault activity. At the same time, the active faults are developed well in the study area, such as the Yingxiu-Beichuan Fault, Huya Fault, Minjiang Fault, Pingwu-Qingchuan Fault and the Maowen Fault, and so on. According to the data supplied by the Science data Center of Resources and Environment of the Chinese Academy of Sciences(www.resdc.cn), and from the DEM data of ASTER GDEM with the resolution of 30 m, the authors classified the influence factors into four sets:seismic factor set including intensity sub-set and epicentral distance sub-set; tectonic factor set including lithology sub-set and fault sub-set; natural environmental factor set including the sub sets of elevation, slope, direction, river and rainfall; human-being activity factor set with the sub-set of distance to highway. The susceptibility of the factors for the landslides induced by the Wenchuan and Lushan earthquakes is then analyzed by using these selected factors based on the GIS tool and the certainty factor(CF)method. The principle influence factors for earthquake-induced landslide are thus determined based on the z values and CF values. Research results show that: