四川汶川MS 8.0大地震地表破裂带的遥感影像解析

2008年5月12日发生于四川盆地西部龙门山断裂带的汶川MS 8.0级大地震造成巨大的人员伤亡和财产损失，并形成了空间上基本连续分布的地表破裂带（地震断层）。根据地表破裂带的解译标志及影像特征，我们充分利用震后中国科学院航空遥感飞机所获取的高分辨率航空遥感图像以及我国台湾福卫-2卫星遥感图像进行详细解译分析，并结合震后的多次野外科学考察与验证，初步查明了四川汶川MS 8.0级大地震所产生地表破裂带的空间分布特征。遥感解译分析表明汶川大地震产生的地表破裂带总计长约300 km，其几何学特征十分复杂，主要沿先存的NE走向活动断裂带呈不连续展布；变形特征以逆冲挤压为主兼具右旋走滑分量。按同震地表破裂带所在断裂带位置，可将其分为两条： 中央地表破裂带：沿映秀-北川断裂带分布，从西南开始呈北东向延伸至平武县水观乡石坎子北东一带，长约230 km，最大垂直位移量达6.0 m左右,最大右旋水平位移达5.8 m；山前地表破裂带：沿灌县-安县断裂带分布，由都江堰市向峨乡一带开始呈北东向延伸至安县雎水镇一带，长约70 km，以逆冲挤压为主，最大垂直位移量可达2.5 m。此外,遥感图像分析还表明上述地表破裂带与地质灾害分布在空间上具有十分密切的相关性,因此,挤压逆冲-走滑型地震断层的致灾效应研究是未来应该加以重视的研究课题。

Spatial Characteristics of the Surface Rupture Produced by the MS 8.0 Wenchuan Earthquake Using High resolution Remote Sensing Imagery

The MS 8.0 Wenchuan earthquake of 12 May 2008 occurred along the Longmenshan fault zone in the western Sichuan Basin, resulting in inestimable casualties and property losses as well as continuous surface ruptures (seismic fault). Based on the detailed interpretation of co-seismic surface ruptures using the post-earthquake high-resolution remote sensing images, which were acquired by the remote sensing airplanes of the Chinese Academy of Sciences and Taiwan FORMOSAT-2 spaceborne sensors, combined with the post-earthquake field investigations, this study ascertains the spatial distribution of the surface ruptures produced by the MS 8.0 Wenchuan earthquake. The results indicate that the great MS 8.0 Wenchan earthquake produced a nearly 300 km-long surface rupture zone with a complicated geometry, and distributes discontinuously along the pre-existing NE-trending active faults. The deformation is characterized mainly by thrust compressing and dextral strike-slip component. The surface ruptures can be divided into 2 zones according to the location of active faults: one is the central surface rupture zone with a length of about 230 km, which distributes along the Yingxiu-Beichuan fault, stretching from southwest of Yingxiu Town of Wenchuan County to northeast of Shikan Town of Pingwu County, with a maximum vertical displacement up to about 6.0 m and the right-lateral horizontal offset up to 5.8 m; the other is the piedmont surface rupture zone with a length of about 70 km, which distributes along the Guanxian-Anxian fault, beginning from the Xiange town of Dujiangyan City, and terminating around the Suishui Town of Anxian County. The deformation is characterized by the thrust faulting with a maximum vertical displacement of 2.5 m. In addition, the analysis of remote sensing image shows that most of the geological disasters such as landslide and collapse distribute along the hanging wall of above-mentioned earthquake fault zones. Therefore, special research should be given to geological hazard effect related to thrust-faulting.