Finite element modelling of crustal anisotropy in volcanic systems using transversely isotropic media

Abstract

Numerical models are essential tools in volcanology for understanding stress redistribution, ground deformation, and eruption precursors associated with magma migration within the crust. Although many models assume an isotropic crust, natural crustal rocks are commonly mechanically anisotropic due to layering, foliation, or aligned fracture networks. This study uses three-dimensional finite element modelling to examine how elastic anisotropy influences stress distribution and surface deformation induced by pressurized magma chambers. The crust is represented as a transversely isotropic medium, capturing directional stiffness without explicitly modelling mechanical layering. Spherical, horizontally elongated, and vertically elongated chambers are simulated under different anisotropy orientations and overpressure conditions. Results show that anisotropy generates asymmetric stress and deformation patterns, including lateral shifts of tensile stress, displacement maxima, and stress rotations of up to 90°. The locations of maximum stress and deformation are largely independent of overpressure and are mainly controlled by chamber geometry and crustal fabric.