地震勘探方法在薄覆盖层区城市活断裂探测中的应用  

The application of seismic exploration method to active faults detection in urban thin overburden area

作　　者：马董伟 MA Dong-Wei(Shengfeng Institute of Geological New Technique Application of Shanghai,Shanghai 201702,China)

机构地区：[1]上海申丰地质新技术应用研究所有限公司

出　　处：《物探与化探》2019年第5期1038-1045,共8页Geophysical and Geochemical Exploration

基　　金：新沂市活动断层探测与地震危险性评价项目(2017)

摘　　要：地震勘探方法是当前探测城市活断层的主要物探方法。在新沂市活断层探测中,由于局部地区覆盖层较薄,单单依靠纵波反射法勘探,只能识别出来自于基岩顶面的反射波。一般情况下,根据地震反射剖面上单个同相轴的变化很难判定断层的准确位置及上断点的埋深。横波反射法分辨率高、分层能力强,能够弥补纵波反射勘探的缺点,因此可以提高勘探的精度;另外,该勘探区内个别断裂两侧存在两种不同年代的地层年代差异较大,两者在速度上有着明显的差异,利用地震层析成像法获得的地震速度剖面,能够反映地下速度结构的变化,可以从另一方面揭示浅埋断层的存在。通过对这几种物探方法取得的成果相互比较和综合分析,并结合地质资料得到了理想的物探成果,取得了良好的勘探效果。Currently,seismic explorations is the main geophysical prospecting method for detecting active fault lines in cities.In the detection of the active faults in Xinyi City,the wave reflected from the top of bed rock can only be recognized using P-wave reflection due to the thin overburden in local area.In general,it is difficult to determine the exact location of a fault and the burial depth of the upper breaking point based on the change of a single coaxial axis in seismic reflection profile.The method of S-wave reflection is characterized by high resolution and strong stratification capability,which can make up for the shortcomings of P-wave reflection exploration,thus improving the precision of exploration.In addition,there exist strata of two different ages on both sides of some faults in this exploration area,and there are obvious differences in velocity between them.The seismic velocity profile obtained by seismic tomography can reflect the changes of underground velocity structures and also reveal the existence of shallow faults.Through this comparison and comprehensive analysis of the results obtained by these geophysical prospecting methods and the combination of geological data,the ideal geophysical prospecting results and sound exploration results are reached.

关 键 词：薄覆盖层 断裂 浅层地震勘探 纵波反射波法 横波反射波法 折射层析成像法 

分 类 号：P631.4[天文地球—地质矿产勘探]