2022年MS_(6.8)泸定地震诱发滑坡中过剩地形的影响  

STUDY ON THE EFFECT OF EXCESS TOPOGRAPHY ON LANDSLIDES INDUCED BY LUDING MS_(6.8)EARTHQUAKE IN 2022

作　　者：邱恒志 马思远 陈晓利[1] QIU Heng-zhi;MA Si-yuan;CHEN Xiao-li(Key Laboratory of Seismic and Volcanic Hazards,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中国地震局地质研究所,活动构造与火山重点实验室,北京100029

出　　处：《地震地质》2024年第4期783-801,共19页Seismology and Geology

基　　金：中国地震局地质研究所基本科研业务专项(IGCEA2202)资助。

摘　　要：地貌演化受到构造活动和河流侵蚀等作用影响。作为地貌演化的重要组成部分,滑坡对于塑造地貌形态起到了重要作用。滑坡发生的本质是坡体平衡受到破坏,而这种不平衡现象可体现为存在过剩地形。2022年9月5日四川省泸定县MS_(6.8)地震诱发了大量山体滑坡,为研究过剩地形对同震滑坡的空间分布提供了一个研究实例。文中基于震后遥感影像对同震滑坡进行了提取,并依据ALOS 12.5m地形高程数据计算了震区过剩地形。此次工作共识别出1485个滑坡(面积约为14.83km^(2)),这些同震滑坡多为浅层滑坡,呈带状集中分布于大渡河两侧。同时,过剩地形的计算结果显示其主要分布在大渡河及其支流的山谷两侧。相关性分析结果表明,高达91.7%的同震滑坡分布在不同厚度的过剩地形分布区。为了进一步研究过剩地形和同震滑坡的空间关系,文中对2008年汶川地震、2013年芦山地震和2014年鲁甸地震等诱发滑坡与过剩地形的空间分布进行了分析,结果表明二者的空间分布具有高度的一致性,显示出过剩地形对同震滑坡空间分布的控制作用。值得注意的是,文中计算获得的泸定地震震区过剩地形的平均高度约为80.0m,明显大于此次地震诱发滑坡的厚度,这意味着此次同震滑坡仅仅是移除了很少部分的过剩地形,据此推测剩余的过剩地形分布区仍是未来潜在的滑坡易发区。Strong earthquakes in mountainous regions are prone to triggering severe geological disasters,such as landslides,collapses,and debris flows.These disasters are characterized by their wide distribution,large scale,and high frequency,making them among the most destructive secondary effects of earthquakes.In recent years,the central and eastern parts of the Qinghai-Tibet Plateau have experienced frequent strong earthquakes,leading to varying degrees of earthquake-induced landslide disasters.Landscape evolution is significantly influenced by tectonic activities and river incising,which alter the materials of hillslopes and their topographic characteristics.Earthquakes can significantly affect the spatial distribution of co-seismic landslides,particularly in areas with excess topography.In tectonically active zones,rock uplift and river erosion gradually increase slope angles and decrease slope stability.Weathering,freeze-thaw cycles,and seismic vibrations can reduce rock strength,leading to slope erosion and landslides.Once these processes occur,the slope tends to reach a critical state of stability,which is characterized by the presence of excess topography.Landslides can rapidly reduce hillside elevations,limiting terrain relief and impacting landform evolution.Excess topography,defined as rock mass inclined at angles greater than a specified threshold,is closely related to unstable slope masses.The essence of a landslide is the disruption of slope equilibrium,often reflected in the presence of excess topography.However,the influence of excess topography on the distribution of co-seismic landslides is not well understood.Earthquake-induced landslides occur when slopes become unstable and slide due to seismic forces.The instability arises when ground motion alters the internal friction angle and cohesion forces along rock mass defects,making them unable to resist the gravitational forces that cause sliding.The weight of the slope material plays a crucial role in this process.As a key component of landscape evolution

关 键 词：2022年MS6.8泸定地震 同震滑坡 过剩地形 滑坡分布 

分 类 号：P315.2[天文地球—地震学]