1887

Abstract

Summary

Anisotropy in the electrical conductivity of the subsurface has been recognized as one of the major difficulties in interpreting Magnetotelluric (MT) data; as it can lead to inaccurate inversion results under simple isotropic assumption. A robust modelling code producing accurate simulation results for anisotropic cases is much needed for the MT community, in order to extract more information from MT data in the inversion process. We present open-source Python package esys-Escript. It is designed to solve mathematical modelling problems using the finite element method (FEM). Its key idea is to formulate the problem in terms of general partial differential equations (PDEs) with proper boundary conditions. Its object-oriented programming style creates a flexible and easy-to-use interface for users to tackle their tasks. esys-Escript has been used to simulate 2D isotopic MT responses with a good agreement with published analytical solutions. Extending from this work, we present an implementation of the MT forward model for anisotropic media using Escript. In order to validate our code, we show anisotropic MT modelling results with the comparison of analytical solutions under an axially anisotropic setting. Then we add a general anisotropic case displaying Escript MT modelling results, validating against published anisotropic MT modelling code.

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/content/papers/10.3997/2214-4609.201900700
2019-06-03
2020-07-05
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References

  1. Codd, A. L. and Gross, L.
    [2018] Electrical Resistivity Tomography using a finite element based BFGS algorithm with algebraic multigrid preconditioning. Geophysical Journal International, 212(3), 2073–2087.
    [Google Scholar]
  2. Guo, Z., Egbert, G. D. and Wei, W.
    [2018] Modular implementation of magnetotelluric 2D forward modeling with general anisotropy. Computers & Geosciences, 118, 27–38.
    [Google Scholar]
  3. Li, Y.
    [2002] A finite-element algorithm for electromagnetic induction in two-dimensional anisotropic conductivity structures. Geophysical Journal International, (148), 389–401.
    [Google Scholar]
  4. Li, Y. and Pek, J.
    [2008] Adaptive finite element modelling of two-dimensional magnetotelluric fields in general anisotropic media. Geophysical Journal International, 175, 942–954.
    [Google Scholar]
  5. Martí, A.
    [2014] The Role of Electrical Anisotropy in Magnetotelluric Responses: From Modelling and Dimensionality Analysis to Inversion and Interpretation. Surveys in Geophysics, 35(1), 179–218.
    [Google Scholar]
  6. Pek, J. and Verner, T.
    [1997] Finite-difference modelling of magnetotelluric fields in two-dimensional anisotropic media. Geophysical Journal International (128), 505–521.
    [Google Scholar]
  7. Qin, L. and Yang, C.
    [2016] Analytic magnetotelluric responses to a two-segment model with axially anisotropic conductivity structures overlying a perfect conductor. Geophysical Journal International, 205(3), 1729–1739.
    [Google Scholar]
  8. Reddy, I. and D, R.
    [1975] Magnetotelluric response of laterally inhomogeneous and anisotropic media. Geophysics, 40, 1035–1045.
    [Google Scholar]
  9. Schaa, R., Gross, L. and du Plessis, J.
    [2016] PDE-based geophysical modelling using finite elements: examples from 3D resistivity and 2D magnetotellurics. Journal of Geophysics and Engineering, 13(2), S59–S73.
    [Google Scholar]
  10. Wannamaker, P. E.
    [2005] Anisotropy Versus Heterogeneity in Continental Solid Earth Electromagnetic Studies: Fundamental Response Characteristics and Implications for Physicochemical State. Surveys in Geophysics, 26(6), 733–765.
    [Google Scholar]
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