【摘要】 探地雷达具有快速、检测范围广、探测深度深、分辨率高及对地表环境无破坏等特点,在活动断层探测应用中具有很大的优势。在简要介绍玉树走滑断裂带活动性的基础上,选择高分辨率的探地雷达对隆宝、昔日达和盘琼沟处断裂带附近的活动断层进行探测。采用时间域有限差分法建立活动断层的数值模型对其雷达波响应特征进行模拟,分析断层在探地雷达剖面上的反射波特征。根据断层的反射波特征解译探地雷达图像,判断断层的位置、走向及空间展布。结合探槽开挖对比,探地雷达图像的解译结果与探槽开挖后的断裂带剖面展示的断层活动性质基本一致。根据隆宝、昔日达和盘琼沟处的探地雷达图像与探槽剖面上断层反射波特征的对比研究,解译了玉树地震震中位置探地雷达剖面上的断层展布。研究表明,探地雷达是一种快速探测活动断层的有效方法,尤其是在地表破裂不明显的区域,不仅可以准确地判断断层的位置、走向及空间展布,还可以将断裂带附近地下岩层的层位信息及探槽断面之外的地表下图像清晰地呈现出来,为以后运用探地雷达探测活动断层提供参考。更多还原

【Abstract】 GPR(Ground Penetrating Radar) has such characteristics as rapidness,wide range,great detection depth and high resolution,with no damage to the surface environment,so it seems to be quite effective in the study of active faults. Based on depicting ac-tive faults along Yushu strike-slip faulted zone,the authors employed high-resolution GPR to delineate active faults in Yushu faulted zone distributed in Longbao,Xirida and Panqionggou. The characteristic responses of electromagnetic waves were simulated on the basis of the numerical model by Finite-difference time-domain method(FDTD),and then the reflected characteristics of active faults on the GPR profiles was summarized. In this way,the GPR images are interpreted and the location,the orientation and the spatial distribution of the active fault can be accurately determined. Combined with exploratory trench cutting,GPR profile is extremely consistent with the trench section. Finally,according to the comparative study of the characteristic responses of electromagnetic waves between the GPR profiles and the trench sections,the GPR images of the earthquake epicenter are interpreted. Preliminary studies show that GPR seem to be an effective and fast technique in detecting active faults,especially in the area without clear evidence of surface rupture. It not only accurately determines the location,the orientation and the spatial distribution of the active fault but also describes the layer in the subsurface and the section outside the trench,thus providing a reference for the detection of active faults by GPR.更多还原