2008汶川大地震极端滑坡事件初步研究

为了分析汶川地震诱发滑坡灾害事件强度和影响,本文以汶川地震诱发滑坡极端事件为线索,在统计分析前10个规模最大、位移最远、危害最重及最大滑坡堰塞湖分布特征的基础上,重点研究前三甲极端滑坡事件的简要特征,初步揭示:(1)汶川地震诱发的极端滑坡事件主要沿龙门山中央断裂(映秀—北川断裂带)和Ⅹ-Ⅺ高烈度地段分布,强震的振动力、地震主传播方向和发震断裂NE向扩展作用是启动极端滑坡事件的主要原因;(2)规模最大的前10个滑坡和距离最大的前10个高速远程滑坡具有很好的重合特征,两者都反映汶川地震诱发的高能量滑坡事件;其中,规模最大的绵竹市安县大光包滑坡,初步估算体积约7.42×108m3,最大运动距离达到3.5km,距离排名第二;距离最大的绵竹文家沟高速远程滑坡,初步估算最大位移为4.2km,其体积约1.5×108m3,规模排名第二,这两个滑坡都属于世界上罕见的大型高能量高速远程滑坡;(3)前10个最大的灾难性滑坡事件,累计导致3751人死亡,单个滑坡引起的人员死亡超过100人,最多的达到1600人,属于世界上罕见的灾难性滑坡事件;(4)潜在危险性最大的10个滑坡堰塞湖,曾经威胁几十万人的生活安全,其中,最大的北川唐家山滑坡堰塞湖,曾经威胁下游绵阳市30万人的生活安全,这些滑坡堰塞湖都及时采取人工开挖措施排除了潜在危险。

STUDY ON CATASTROPHIC LANDSLIDES TRIGGERED BY 2008 GREAT WENCHUAN EARTHQUAKE,SICHUAN,CHINA

In order to analyze the intensity and influence of landslides triggered by the great Wenchuan earthquake,a central idea in this paper is to focus on the first 3 extreme landslide events among the first 10 landslides with the largest volume,the longest sliding run out,the most serious hazard and the largest landslide dammed lake. The followings are revealed: (1)the extreme landslides are mainly distributed along the Longmenshan central fault and in the areas with high intensity of Ⅹ-Ⅺ; the strong vibration force,the main propagation direction of earthquake and the NE expansion of seismic fault are the major reasons for the initiation of extreme landslide events; (2)generally,the first 10 landslides both have the largest volume and the longest sliding long run out,among them,the Daguangbao landslide,located at Anxian county,Mianzhu city,is the first one,with the volume of 742 million m3 and the sliding long run out of 35 km; the second one is the Wenjiagou landslide in Qingping county,Mianzhu city,with the volume of 150 million m3 and the sliding run out of 42 km. The above two landslides are all rare rapid and long run out landslides with high energy in the world; (3)the first 10 catastrophic landslides totally caused 3751 deaths,and over 100 deaths are due to individual event,with the maximum of 1600; (4)the first 10 landslide dammed lakes with potential risk had threatened the lives safety for hundreds of thousands of people; among them,the Tangjiashan dammed lake is the largest one,which had imperiled 03 million peoples life of Mianyang city; fortunately,timely measures such as artificial excavation had been taken for removing of potential risk．