Hybrid mesh for magnetotelluric forward modeling based on the finite element method

Area of Science:

• Geophysics
• Computational Electromagnetics

Background:

• Unstructured tetrahedral grids are used in magnetotelluric (MT) finite element (FE) forward modeling for complex anomalies.
• Near-surface refinement in tetrahedral grids leads to excessive meshes and high computational cost (DoF).

Purpose of the Study:

• To develop a hybrid mesh to reduce computational cost in MT forward modeling.
• To improve modeling efficiency and accuracy, particularly for high-frequency data and complex terrains.

Main Methods:

• Developed a hybrid mesh using triangular prisms for the near-surface and tetrahedrons for the deep area.
• Tested the hybrid mesh on layered, DTM1, and terrain relief models.
• Compared results with conventional tetrahedral meshes at similar degrees of freedom (DoF).

Main Results:

• The hybrid mesh significantly improved modeling efficiency, especially for high-frequency data.
• Achieved higher accuracy compared to tetrahedral meshes with similar DoF.
• Demonstrated adaptability to complex geoelectric models with significant terrain fluctuations.

Conclusions:

• The hybrid mesh offers a computationally efficient and accurate alternative for MT forward modeling.
• This method is well-suited for complex geological scenarios and varying terrain.
• Reduces the computational burden associated with detailed near-surface modeling.