3D Magnetotelluric Inversion with Triaxial Anisotropy and Its Implementation in Julia
Abstract
A lot of 3D magnetotelluric (MT) inversion algorithms have been developed over the past few decades, and most of the corresponding codes are written in the Fortran language because Fortran is relatively convenient and highly efficient for numerical calculations. However, nowadays there are several high-level programming languages much more convenient than Fortran for implementing the numerical algorithms involved in MT inversion, such as MATLAB and Python, and they have been used for developing MT inversion software in recent years. Recently, a new high-level programming language with strong focus on scientific computing, Julia, has been developed. Julia has a powerful syntax that is as expressive as MATLAB. However, unlike typical interpreted dynamic languages, it also has a just-in-time (JIT) compiler and a complete type system, the combination of which allows it to be highly efficient, even to approach the performance of traditional statically-compiled languages like C and Fortran. In this contribution, we present an open-source package implemented in Julia for 3D inversion of MT data with triaxial anisotropy. For forward modeling, a 3D mimetic finite-volume (FV) method is employed. As a consequence, it is rather straightforward to take triaxial anisotropy into account. For inversion, the inexact Gauss Newton (GN) search has been implemented. All algorithms are expressed in pure matrix form and implemented modularly using the Julia language. As a consequence, the code is not only easy to read, maintain and extend, but also highly efficient. The effectiveness of the developed code is demonstrated using synthetic datasets.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP13B0594H
- Keywords:
-
- 0925 Magnetic and electrical methods;
- EXPLORATION GEOPHYSICS;
- 1515 Geomagnetic induction;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 3006 Marine electromagnetics;
- MARINE GEOLOGY AND GEOPHYSICS;
- 3914 Electrical properties;
- MINERAL PHYSICS