Three-dimensional magnetotelluric inversion considering electrical anisotropy with synthetic and real data

Xiao，Qibin1; Yu，Guo2; Dong，Zeyi1; Sun，Zelin1

2022-05-01

10.1016/j.pepi.2022.106876

PHYSICS OF THE EARTH AND PLANETARY INTERIORS   影响因子和分区

0031-9201

1872-7395

Electrical anisotropy increases the non-uniqueness of magnetotelluric (MT) inversions. However, it is still useful to develop MT anisotropic inversion to provide new knowledge for this field. In this study, we developed a three-dimensional (3-D) MT inversion code considering electrical anisotropy. The forward procedure is based on a staggered-grid finite-difference method and solves the governing equation for the electric fields with a direct method. The values of a traditional objective function and its gradient could then be calculated. The inversion procedure was completed with a well-developed subroutine of non-linear conjugate gradient method. Synthetic tests for different isotropic models indicate the validity of this inversion code. Furthermore, we performed 3-D anisotropic inversions for synthetic and real data. The results indicate that vertical resistivity is still indistinguishable in the anisotropic inversion results. In our synthetic tests, it becomes more difficult to recover low-resistivity components of anisotropic anomalies as the depth increases, and the vertical sizes of anisotropic anomalies are reduced, as characterized by a much shallower bottom boundary. The anisotropic strike angle is not as stable as the principal resistivities in the inversion process. Under the same changes in model parameters, the strike angle may cause larger deviations of the responses than the principal horizontal resistivities. With this code, we revisited the field data collected at the northern margin of the Tibetan Plateau. The inversion results indicate a possible anisotropic anomaly exists below the boundary between the plateau and its northern neighbor. This anisotropic anomaly could represent an area of concentration of shear deformation.

Electrical anisotropy Magnetotelluric Non-linear conjugate gradient method Northern Tibetan Plateau Three-dimensional inversion

SCI ; EI

英语

其他

National Natural Science Foundation of China[41274080];National Natural Science Foundation of China[41774080];National Natural Science Foundation of China[41974091];

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000807537300001

ELSEVIER

20221611976310

Anisotropy ; Electric fields ; Finite difference method ; Magnetotellurics

Geophysics:481.3 ; Electricity: Basic Concepts and Phenomena:701.1 ; Mathematics:921 ; Numerical Methods:921.6 ; Physical Properties of Gases, Liquids and Solids:931.2

GEOSCIENCES

2-s2.0-85128181475

Scopus

1.State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing,100029,China
2.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,Guangdong,518055,China

Xiao，Qibin,Yu，Guo,Dong，Zeyi,et al. Three-dimensional magnetotelluric inversion considering electrical anisotropy with synthetic and real data[J]. PHYSICS OF THE EARTH AND PLANETARY INTERIORS,2022,326.

Xiao，Qibin,Yu，Guo,Dong，Zeyi,&Sun，Zelin.(2022).Three-dimensional magnetotelluric inversion considering electrical anisotropy with synthetic and real data.PHYSICS OF THE EARTH AND PLANETARY INTERIORS,326.

Xiao，Qibin,et al."Three-dimensional magnetotelluric inversion considering electrical anisotropy with synthetic and real data".PHYSICS OF THE EARTH AND PLANETARY INTERIORS 326(2022).