地震破裂带特殊部位大型滑坡及其基于构造地貌发生模型的机制解释:以东河口抛射型滑坡为例  

Huge landslides occurred at the special places of the coseismic rupture and their mechanism explanation based on the formation model of tectonic-geomorphology:A case study of Donghekou ejection landslide.

作　　者：袁仁茂[1] 谭锡斌[1] 陈桂华[1] 徐锡伟[1] 

机构地区：[1]中国地震局地质研究所国家地震活断层研究中心,北京100029

出　　处：《地学前缘》2010年第5期243-253,共11页Earth Science Frontiers

基　　金：国家自然科学基金项目(40821160550;40702048)

摘　　要：汶川地震在龙门山地区激发了大量的次生地质灾害,其中尤以滑坡灾害分布最为广泛和严重。在所有滑坡灾害中,东河口滑坡发生在北川破裂带的北东端点,具有相当的特殊性,并造成了大量的生命财产损失。东河口滑坡是一种抛射型滑坡,具有与其他如重力或者降雨作用导致的滑坡不同的特点,即没有统一连续的滑动面,由上部比较深陡和下部比较浅缓的截然分开的两部分组成,在强地震加速度的作用下,滑坡体被抛射并在与地面发生碰撞之前沿抛物线轨迹运行。文章综合分析了东河口抛射型滑坡发生的地质地貌条件,并解释了该抛射型滑坡发生的动力源机制。结果显示,东河口滑坡区的滑坡带和翼状裂隙带在北川破裂带两侧的规则分布受控于断层的运动方式和滑坡的空间分布位置;此外,除地震动水平加速度和地质地貌条件外,垂直加速度和断层的运动方式对地震滑坡的激发也起着重要的作用。On May 12,2008,Wenchuan Ms 8.0 earthquake triggered widespread damaging landslides in many parts of the Longmenshan area.The Donghekou ejection landslide was a special one of them and caused the great loss of life,which was located at Donghekou village,Qinchuan,Sichuan Province.The Beichuan rupture terminated at there.As an ejection landslide occurred at the special place,it is different from landslides caused by gravity and rainstorm： there was no uniform continuous slide face;it was comprised of the upper deep slide face and the lower shallow slide face;and the landslide started from the ejected body because of the large seismic horizontal and vertical acceleration.Studies indicate that the regular distribution of the landslide zone and domino-like ground tension cracks zone at the both sides of the Beichuan rupture was controlled by the forming process of the ground rupture,namely the type of active fault moving.The phenomenon suggests that researchers should consider the vertical acceleration and the occurring place,besides the shaking,horizontal acceleration and geomorphological and geological conditions,when evaluating the earthquake-triggered huge landslides.

关 键 词：汶川地震 东河口抛射型滑坡 破裂带端点 走滑断层 

分 类 号：P642.22[天文地球—工程地质学] P315.2[天文地球—地质矿产勘探]