三维断层模型的MT倾子响应数值模拟  

Numerical simulation of MT tipper response based on 3D fault models

作　　者：林兴龙 顾观文 牛兴国 武晔 王顺吉 王英杰 曹来 LIN Xing-Long;GU Guan-Wen;NIU Xing-Guo;WU Ye;WANG Shun-Ji;WANG Ying-Jie;CAO Lai(School of Earthquake Sciences,Institute of Disaster Prevention,Sanhe 065201,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,China;Langfang Key Laboratory of Earth Exploration and Information Technology,Sanhe 065201,China;Inner Mongolia Nonferrous Geology and Mining(Group)Geophysical Exploration Co.,Ltd.,Hohhot 010010,China)

机构地区：[1]防灾科技学院地球科学学院,河北三河065201 [2]河北省地震动力学重点实验室,河北三河065201 [3]廊坊市地球探测与信息技术重点实验室,河北三河065201 [4]内蒙古有色地质矿业(集团)物探勘查有限责任公司,内蒙古呼和浩特010010

出　　处：《物探与化探》2025年第1期82-99,共18页Geophysical and Geochemical Exploration

基　　金：中央高校创新团队项目(ZY20215108);河北省高等学校科学技术研究项目(ZC2022056);中国长江三峡集团有限公司资助科研项目(0799217);廊坊市科技支撑计划项目(2023013184);河北省硕士在读研究生创新能力培养项目(CXZZSS2023184)。

摘　　要：倾子矢量作为大地电磁测深法中的一个重要参数,适用于推断介质横向不均匀的断裂构造。地下断层构造一般具有三维性和复杂性的特点,为了揭示三维断层模型的大地电磁倾子响应特征,本文基于矢量有限元法开展了三维断层模型的大地电磁倾子响应数值模拟。首先,通过理论模型试算,并与前人的有限元法计算结果对比,验证了三维倾子正演计算程序的正确性。在此基础上,分别对直立断层、正断层、逆断层和走滑断层4种典型的三维断层模型进行正演模拟,获得倾子响应的实部、虚部、振幅和相位。模拟结果表明:在两种极化模式下,倾子实部、虚部和振幅响应特征对4种不同类型断层的性质、走向、倾向等信息反映效果明显,同时又表现了断层横向不均匀的边界位置,可作为判别断层类型和特征的重要依据;相比于倾子实部、虚部和振幅的响应特征,倾子相位响应特征较为复杂,难以有效反映断层特征信息。The tipper vector,a significant parameter in magnetotelluric(MT)sounding,is applicable to infer fault structures that cause lateral inhomogeneity of media.Subsurface faults typically exhibit three-dimensionality and complexity.To reveal the MT tipper response characteristics in 3D fault models,this study conducted numerical simulations of the MT tipper response in 3D fault models based on the vector finite element method.First,the validity of the 3D tipper forward modeling program was verified through theoretical model calculations and comparisons with previous finite element results.Subsequently,four typical 3D models for vertical,normal,reverse,and strike-slip faults were employed for forward modeling,obtaining the response characteristics of the real part,imaginary part,amplitude,and phase of the tipper.The simulation results are as follows:(1)In two polarization modes,the response characteristics of the real part,imaginary part,and amplitude of the tipper effectively reflect the properties,strikes,and dip directions of the four different faults while indicating the location of the laterally inhomogeneous boundaries,thus serving as a significant basis for discriminating fault types and characteristics;(2)In contrast,the relatively complex response characteristics of the phase fail to effectively mirror the fault characteristics.

关 键 词：大地电磁测深 三维断层模型 倾子矢量 矢量有限元 数值模拟 

分 类 号：P631.4[天文地球—地质矿产勘探]