A two-step three dimensional marine magnetotelluric inversion method with considering rugged seafloor topography:Synthetic studies  

作　　者：Pengfei LIANG Qingyun DI Changmin FU Ruo WANG Qihui ZHEN Zhe YUN Jiagang ZHANG 

机构地区：[1]CAS Engineering Laboratory for Deep Resources Equipment and Technology,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China [3]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [4]Exploration Surveying Institute of Baogang Group,Baotou 014010,China

出　　处：《Science China Earth Sciences》2023年第4期765-780,共16页中国科学（地球科学英文版）

基　　金：supported by the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.ZDZBGCH2018006);the National Natural Science Foundation of China(Grant No.41874088);the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA14050100)。

摘　　要：Inversion of magnetotelluric(MT) responses has been used to explore the electrical conductivity distribution of the Earth’s interior. In three-dimensional(3-D) inversions, it is significant to use a good initial model, because final model obtained by most 3-D inversion methods is influenced by the initial model. Although uniform initial models are widely used in 3-D inversions, one-dimensional(1-D) initial models are alternatives, which could more appropriately represent the actual conductivity variations in the Earth’s interior. This study presents a two-step 3-D inversion method, especially for marine cases. This inversion method first concentrates on obtaining a 1-D initial model and then inverts for 3-D conductivity structures with it, in both of which the 3-D topography is carefully taken into consideration. This method was tested by synthetic models of different topography variations(depression-shaped, smoothly varying, channel-shaped and square-shaped plateau topography) and of heterogeneous layers with different checkerboard-type anomalies(sharp or smooth lateral conductivity variations) embedded in1-D model of depth-dependent conductivity. The comparisons were done about obtaining an initial model by the proposed method and that inverted from the corrected responses. The results of 3-D inversions by using the method of this study were also compared to that with different uniform initial models. Results of synthetic tests and comparisons were discussed by using directional information of newly introduced model-vector parameters. The performance and validity of this method was verified.It also revealed that some of the newly introduced model-vector parameters could be used to show the convergence of inversions and help to select inverse model.

关 键 词：MAGNETOTELLURIC Integral equation TOPOGRAPHY INVERSION Convergence 

分 类 号：P631.325[天文地球—地质矿产勘探] P714.8[天文地球—地质学]