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3D magnetotelluric modelling including surface topography
Author(s) -
Nam Myung Jin,
Kim Hee Joon,
Song Yoonho,
Lee Tae Jong,
Son JeongSul,
Suh Jung Hee
Publication year - 2007
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.2007.00614.x
Subject(s) - magnetotellurics , jacobian matrix and determinant , preconditioner , finite element method , hexahedron , geology , ridge , geometry , biconjugate gradient method , electric field , surface (topology) , transverse plane , mechanics , mathematical analysis , physics , mathematics , computer science , engineering , linear system , electrical resistivity and conductivity , conjugate residual method , gradient descent , structural engineering , paleontology , quantum mechanics , machine learning , artificial neural network , thermodynamics
An edge finite‐element method has been applied to compute magnetotelluric (MT) responses to three‐dimensional (3D) earth topography. The finite‐element algorithm uses a single edge shape function at each edge of hexahedral elements, guaranteeing the continuity of the tangential electric field while conserving the continuity of magnetic flux at boundaries. We solve the resulting system of equations using the biconjugate gradient method with a Jacobian preconditioner. The solution gives electric fields parallel to the slope of a surface relief that is often encountered in MT surveys. The algorithm is successfully verified by comparison with other numerical solutions for a 3D‐2 model for comparison of modelling methods for EM induction and a ridge model. We use a 3D trapezoidal‐hill model to investigate 3D topographic effects, which are caused mainly by galvanic effects, not only in the Z xy mode but also in the Z yx mode. If a 3D topography were approximated by a two‐dimensional topography therefore errors occurring in the transverse electric mode would be more serious than those in the transverse magnetic mode.