浅层人工地震探测揭示的夏垫断裂西南段特征

浅层人工地震方法是针对厚覆盖区探测断裂的一种不可替代的技术。为查明夏垫断裂西南段的空间位置、性质及其活动性,2016年底对跨夏垫断裂西南段进行了高分辨率的浅层人工地震探测,获得三条480 m深度范围内地下结构图像的地震剖面,揭示了夏垫断裂西南段的形态\,特征以及空间位置。

Features of the Southwest Segment of Xiandian FaultRevealed through Shallow Seismic Prospecting

Xiadian Fault is one of the main faults in the North China Plain. Few studies, however, have focused on the southwestern segment of Xiadian Fault. In this work, the shallow seismic prospecting method was applied to study the spatial location, characteristics, and activity of the southwest segment of Xiadian Fault. Three shallow reflection profiles were detected within the depth of 480 m. The seismic data acquisition system USES STRTAVISOR NZXP96 is produced in the United States and has the advantages of high resolution and anti-interference. Moreover, the data acquisition method of small track spacing and additional channels were adopted in this study to detect structures over an extensive depth range and obtain high-resolution detection results. An extended permutation test was performed for the selection of reasonable data acquisition parameters. The working parameters of the seismic section were finally determined through experiments and comprehensive analysis. The seismic wave was stimulated with a 70 kg impact ramming source, which was excited 18-20 times at each point. Data processing was performed with Vista2D/3D seismic processing software. Results showed that the southwest segment of Xiadian Fault consists of three flower-like faults with depths of 280 m and bandwidths of 50-60 m. The faults disrupt the Upper Pleistocene strata and terminate upward at the depth of 96-116 m. The active age of the faults is from the early to the middle stages of the Late Pleistocene.