Two-dimensional magnetotelluric inversion using unstructured triangular mesh implemented in Julia
Dieno Diba (a), Nurhasan (b*), Makoto Uyeshima(a), and Yoshiya Usui(a)

a) Earthquake Research Institute, the University of Tokyo, 1 - 1 - 1 Yayoi, Bunkyo, Tokyo 113-0032, Japan
b) Physics Department, Bandung Institute of Technology, Jl. Ganesa No.10, Bandung, West Java 40132, Indonesia
*nurhasan[at]itb.ac.id

Abstract

We have developed a 2-D magnetotelluric inversion code tailored for unstructured triangular meshes, developed using Julia, a high-level, high-performance programming language designed for scientific and numerical computation. The forward modeling engine utilizes a node-based finite element method to solve electromagnetic fields throughout the modeling domain. The inversion process employs the Gauss-Newton optimization algorithm, iteratively updating the model via the minimization of a regularized least-squares objective function. We verified the accuracy of the forward modeling using two reference models and performed a synthetic inversion experiment to validate our inversion method and stress the necessity of accurately handling topography-influenced data. Through its application to constructing an electrical resistivity model beneath the northwestern end of Sumatra Island, Indonesia, we demonstrated the practicality of our code for inverting field datasets.

Keywords: Magnetotelluric, 2D Inversion, Resistivity

Topic: Earth and Planetary Sciences