A Hybrid Meshing Strategy for 3D Magnetotelluric Modelling, Including Shallow Sea

초록

Interpretation of magnetotelluric data acquired near coastlines is challenging due to the distortion of electromagnetic fields caused by the sea effect. Specifically, it is essential to accurately simulate the propagation of electromagnetic fields around the land-sea and air-sea boundary. To properly address the sea effect from the shallow sea, we present a hybrid edge-based finite element method that combines prismatic and tetrahedral elements with vector shape functions. The 3D mesh incorporates prismatic elements to stably obtain enough vertical resolution for the land-sea and air-sea boundary, whereas tetrahedral elements are used for thicker subsurface volumes. The proposed method is demonstrated using synthetic data from a simple 1D/2D model for which analytic/pseudo-analytic solutions can be obtained and used as reference data. These examples show that the proposed method achieves computational efficiency while maintaining accuracy across domains with thin geometries.

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