Three‐Dimensional Inversion of Magnetotelluric Data for a Resistivity Model With Arbitrary Anisotropy

Kong, Wenxin; Tan, Handong; Lin, Chang-Hong; Unsworth, Martyn; Lee, Benjamin; Peng, Miao; Wang, Mao; Tong, Tuo

doi:10.1029/2020jb020562

Cited by 23 publications

(5 citation statements)

References 49 publications

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“…However, the high computational costs associated with global optimization algorithms limit their practical application in 3-D electrical resistivity inversion problems [11,14,15]. Deterministic methods such as the Gauss-Newton method [16], limited memory quasi-Newton method [17], and conjugate gradient method [18][19][20][21] are the popular approaches for the 3-D electrical resistivity inversion due to their promising performance in terms of result accuracy, stability, and convergence speed [8,11,22].…”

Section: Introductionmentioning

confidence: 99%

Fast Initial Model Design for Electrical Resistivity Inversion by Using Broad Learning Framework

Tao,

Han,

Yang

et al. 2024

Minerals

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The electrical resistivity method is widely used in near-surface mineral exploration. At present, the deterministic algorithm is commonly employed in three-dimensional (3-D) electrical resistivity inversion to obtain subsurface electrical structures. However, the accuracy and efficiency of deterministic inversion rely on the initial model. In practice, obtaining an initial model that approximates the true subsurface electrical structures remains challenging. To address this issue, we introduce a broad learning (BL) network to determine the initial model and utilize the limited memory quasi-Newton (L-BFGS) algorithm to conduct the 3-D electrical resistivity inversion task. The powerful mapping capability of the BL network enables one to find the model that elucidates the actual observed data. The single-layer BL network makes it efficient and easy to realize, leading to much faster network training compared to that using the deep learning network. Both the synthetic and field experiments suggest that the BL framework could effectively obtain the initial model based on observed data. Furthermore, in comparison to using a homogeneous medium as the initial model, the L-BFGS inversion with the BL framework-designed initial model improves the inversion accuracy of subsurface electrical structures and expedites the convergence speed of the iteration. This study provides an effective approach for fast initial model design in a data-driven manner when the prior information is unavailable. The proposed method can be useful in high-precision imaging of near-surface mineral electrical structures.

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Section: Introductionmentioning

confidence: 99%

Fast Initial Model Design for Electrical Resistivity Inversion by Using Broad Learning Framework

Tao,

Han,

Yang

et al. 2024

Minerals

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show abstract

“…Therefore, the presence of electrical anisotropy may indicate damage zones (Chesley et al., 2019) and provide useful information about the architecture and deformations associated with major strike‐slip faults. At present, applications of magnetotelluric (MT) anisotropic inversion to real data have been reported worldwide (Baba et al., 2006; Comeau et al., 2020; Kong et al., 2021; Le Pape et al., 2012; Pek et al., 2011; Rong et al., 2022; Xiao et al., 2022; Yu et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

Crustal Electrical Anisotropic Structure of the Altyn Tagh Fault in the Subei Area, NW China: Implications for Fault Zone Architecture

Dong,

Xiao,

Sun

et al. 2024

JGR Solid Earth

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The fault zone architecture may provide reliable information about the deformations in both on‐fault and off‐fault media. The outer damage zones of faults may extend for kilometers and exhibit structural anisotropy, which potentially causes electrical anisotropy in rocks. Thus, electrically anisotropic structures may indicate the dimensions and extent of fault damage zones. We investigated the electrical anisotropic structure of the sinistral Altyn Tagh fault (ATF), NW China, using magnetotelluric data collected in and around the Subei Basin. Our three‐dimensional resistivity model reveals widespread anisotropic anomalies at depths <∼5 km. The directions of the minimum horizontal resistivity values of the anomalies inside the Qilian Shan southeast of the ATF are dominantly subparallel to the fault traces at the surface. At deeper levels (∼15–19 km and ∼33–43 km), the anisotropic anomalies are mainly concentrated near the northern strand of the ATF (NATF) and the North Yemahe fault (NYMF) in the northeastern Subei area. The mid‐lower crust (∼33–43 km) inside the Qilian Shan is characterized by isotropy or weak anisotropy with low resistivities (∼10 Ωm), which deviate significantly from the values along the NATF. Our results indicate the presence of a ∼30 km wide off‐fault damage zone along the NATF and NYMF in the shallow crust that thins downward to the lower crust. We propose that the distribution of anisotropic anomalies is influenced primarily by neighboring faults. An independent deformation model could be appropriate for evaluating the relationships between the ATF and thrust faults within the Qilian Shan.

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“…Since then, several technique revolutions greatly promoted the development of MT and its applications, mainly including the robust estimation of MT response functions e.g., [ 6 , 7 ], the realization and removal of the galvanic distortions of MT data due to near-surface inhomogeneities e.g., [ 8 , 9 , 10 ], developments in two-dimensional (2D) and three-dimensional (3D) MT inversion with electrical isotropy or anisotropy e.g., [ 11 , 12 , 13 , 14 ], and the electrical measurements of major minerals in the crust and mantle in the laboratory at high temperatures and pressures e.g., [ 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

A Review of Subsurface Electrical Conductivity Anomalies in Magnetotelluric Imaging

Lin

Yang

Han

et al. 2023

Sensors

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After 70 years of development, magnetotelluric (MT), a remote sensing technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration and the deep tectonic evolution of the Earth. The electrical resistivity anomalies and their quantitative interpretation are closely related to or even controlled by the interconnected high-conductivity phases, which are frequently associated with tectonic activity. Based on representative electrical resistivity studies mainly of the deep crust and mantle, we reviewed principal electrical conduction mechanisms, generally used conductivity mixing models, and potential causes of high-conductivity including the saline fluid, partial melting, graphite, sulfide, and hydrogen in nominally anhydrous minerals, and the general methods to infer the water content of the upper mantle through electrical anomaly revealed by MT.

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Three‐Dimensional Inversion of Magnetotelluric Data for a Resistivity Model With Arbitrary Anisotropy

Cited by 23 publications

References 49 publications

Fast Initial Model Design for Electrical Resistivity Inversion by Using Broad Learning Framework

Fast Initial Model Design for Electrical Resistivity Inversion by Using Broad Learning Framework

Crustal Electrical Anisotropic Structure of the Altyn Tagh Fault in the Subei Area, NW China: Implications for Fault Zone Architecture

A Review of Subsurface Electrical Conductivity Anomalies in Magnetotelluric Imaging

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