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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