Stable Calculation of Responses for a Plane Electromagnetic Wave in an Anisotropic Layered Media for the Modeling of Magnetotelluric Data

Research in multi-dimensional magnetotelluric (MT) modeling and inversion, particularly within anisotropic media, is gaining substantial interest.One-dimensional (1-D) modeling is utilized as boundary conditions necessary for accurate 2-D or 3-D anisotropic modeling.Based on Maxwell's equations and interface boundary conditions, we developed a new algorithm to calculate electromagnetic fields for both 1-D isotropic and anisotropic layered models.However, this algorithm encounters stability issues at considerable depths or within exceptionally thick layers.To address these challenges, we introduced two stabilization strategies.The first strategy alters the exponential terms in the plane-wave solutions to mitigate instabilities, while the second evaluates each layer's contribution to numerical instability, replacing problematic thick layers with an infinite half-space.Through numerical tests on a four-layer anisotropic model, these strategies proved effective, ensuring stable computations of electromagnetic fields at any depth and in configurations with thick layers, thereby enhancing the model's applicability for in-depth anisotropic analyses.