微动和浅震反射技术在威宁-水城断裂构造隐伏地段的探测应用  

Application of Fretting and Shallow Seismic Reflection Techniques in Detecting Conceal Section in Weining-Shuicheng Fault Structure

作　　者：邱鹏 王家海 QIU Peng;WANG Jia-hai(Guizhou Institute of Earthquake Engineering,Guiyang 550001,Guizhou China)

机构地区：[1]贵州省工程防震研究院,贵州贵阳550001

出　　处：《贵州地质》2023年第2期134-139,共6页Guizhou Geology

基　　金：贵州省地震局地震科技基金项目([2023]03号);贵州省科技支撑计划项目(黔科合支撑[2020]4Y053号)联合资助。

摘　　要：威宁-水城断裂近年来地震较为频繁,历史地震最大震级为5.5级,为贵州地震发育较为频繁的一条较大断裂。本文为探查该断裂的隐伏部位的延续,进而判定该断裂隐伏段的位置、走向、倾向、断距等特征,利用微动和浅层地震反射两种物探方法对威宁-水城断裂重点位置进行精确定位。由于面波干扰的影响,根据地震反射剖面很难准确判定浅地表断层的精确位置。本文根据浅地表地层的错断往往会引起地层横向的速度变化的原理,利用微动方法提取2-5Hz频率范围的瑞雷面波相速度频散曲线,再利用面波层析成像方法反演获取面波二维相速度图像,从而反映出浅地表地层速度结构的变化,可以从另一方面揭示浅地表地层断层的精确位置。将这两种方法同时应用于威宁-水城断层勘探中,可在一定程度上弥补浅层地震反射勘探方法上判定断层浅地表地层精确位置上的不足。同时根据两种物探方法判断断层深浅位置不同,使两种方法能够相互验证。Small earthquakes and microearthquakes often occur near the Weining-Shuicheng fault,especially in the Weining area.In recent years,small earthquakes are more frequent,and historical earthquakes are also controlled at the western end of the fault,with the maximum magnitude of 5.5.In this paper,two geophysical methods of fretting and shallow seismic reflection are used to precisely locate the key positions of weining-Shuicheng fault.The features of surface fault distribution in the study area and conceal condition of 2 physical prospecting method are compared.It is difficult to determine the exact location of the fault only according to the variation of a single in-phase axis on the seismic reflection profile.According to the shallow strata fault fault often causes formation of lateral velocity change,in this paper,using the method to extract 2-5 Hz frequency Rayleigh wave celerity frequency scattering curve,then to get the wave two-dimensional phase velocity image by use surface wave tomography method.By reflect the change of underground velocity structure,it can find out the exact position of shallow fault in another side.If the 2 methods are used in the Weining-Shuicheng fault exploration in the meantime,it will make up for the deficiency of shallow seismic reflection prospecting method in exact fault position determination to a certain extent.

关 键 词：浅层地震反射 威宁-水城断裂 微动探测 

分 类 号：P631.4[天文地球—地质矿产勘探] P542.3[天文地球—地质学]