Three-Dimensional Joint Inversion of MT and Teleseismic Travel Time Data Using Local Pearson Correlation Constraint on Different Model Discretization

Magnetotelluric (MT) and teleseismic tomography are critical techniques in deep Earth exploration for geodynamic studies, internal energy circulation, plate tectonics, volcanic systems, and so on. However, due to the uneven data distribution, the inherent nonuniqueness of inversion, and differing sensitivities to subsurface media, the velocity and resistivity structures derived from independent inversions often exhibit substantial discrepancies and contradict conventional geological understanding. To address these issues, we propose a novel 3-D joint inversion method for MT and teleseismic travel time data, applicable to different types of grid discretization. The method first establishes a parameter mapping for different grid types. Then, a joint inversion framework based on the local Pearson correlation constraints (LPCCs) is developed using a virtual grid technique. The inversion alternately updates the resistivity and velocity models by ensuring structural similarity between them. Numerical experiments demonstrate that the proposed method can effectively integrate the advantages of both techniques, and enhance resolution and stability. Additionally, the tests on hyperparameter selection provide guidance for optimizing joint inversion parameters. Finally, the developed joint inversion method is applied to MT and teleseismic travel time data in southeastern Australia and yields a constrained 3-D resistivity and velocity model of the region. The results offer significant theoretical and practical insights into the lithospheric structure, the magma transport pathways, and the geodynamic processes in this area.