【摘要】 "5.12"汶川大地震具有震级高、震源浅、破坏性强、次生地质灾害严重的特点。通过灾后对地震地质灾害的现场调查和遥感解译,共获得地质灾害点11308处,对地震地质灾害发育分布有了总体认识。在此基础上,利用GIS技术对地震地质灾害的分布与距发震断裂距离坡度、高程、岩性等因素的关系进行统计分析。研究得出:(1)地震地质灾害在区域上具有沿发震断裂带呈带状分布和沿河流水系成线状分布的特点;(2)地震地质灾害分布具有明显的上盘效应,发震断裂上盘地质灾害发育密度明显大于下盘,且上盘强发育带宽度约为10km;(3)地形坡度是地震地质灾害发育的控制性因素之一,绝大部分的灾害集中在坡度20°～50°的范围内;(4)地震地质灾害与高程和微地貌具有很好的对应关系,大部分灾害发生在高程1500～2000m以下的河谷峡谷段,尤其是峡谷段的上部(即宽谷向峡谷的转折部位),单薄的山脊以及孤立或多面临空的山体对地震波最为敏感,具有显著的放大效应,这些部位崩塌滑坡最为发育;(5)不同的岩性与地质灾害的发育虽然没有显著的对应关系,但却决定了地质灾害的类型,通常情况下,滑坡多发生在软岩中,而硬岩中多发生的是崩塌。更多还原

【Abstract】 As Wenchuan earthquake was of high magnitude and shallow seismic focus,it caused considerable damage and thousands of geohazards. After a field investigation and the interpretation of remote-sensing images and aerial photographs taken after the earthquake,11 308 earthquake-induced geohazards have been obtained;and the general distribution situation of the geohazards has been learnt. Then,the distribution of these geohazards was investigated statistically using GIS techniques to determine how the occurrence of geohazards correlates with distance from the coseismic fault,slope steepness,elevation and rock type. The main results of this research can be summarized as follows. (1) The geohazards triggered by earthquake show the feature of zonal distribution along the coseismic fault and linear distribution along the rivers. (2) The distribution of earthquake-induced geohazards has marked hangingwall effect,for the geohazard concentration in the hangingwall of coseismic fault is obviously higher than that in the footwall and the width of strong development zone in the hangingwall is about 10 km. (3)the slope steepness is a main factor which controls the development of earthquake-induced geohazards and a vast majority of geohazards are distributed within the range of 20° to 50°. (4) The earthquake-induced geohazards have corresponding relationship with the elevation and micro-landform;for most hazards occur in river valley and canyon section below the elevation of 1 500 to 2 000 m,particularly in the upper segment of canyon section (namely,the turning point from the dale to the canyon). Thin ridge,isolated or full-face space mountains are most sensitive to the seismic wave,and have striking amplification effect. In these areas,collapses and landslides are most likely to occur. (5) The research also shows that different lithologies have no marked corresponding relationship with the development of geohazards,but it determines the types of geohazards. Usually,landslides occur in soft rocks,while collapses occur in hard rocks.更多还原