Elasto-plastic modeling of volcano ground deformation

Abstract

Elasto-plastic models for pressure sources in heterogeneous domain were constructed to describe, assess, and interpret observed deformation in volcanic regions. We used the Finite Element Method (FEM) to simulate the deformation in a 3D domain partitioned to account for the volcano topography and the heterogeneous material properties distribution. Firstly, we evaluated the extent of a heated zone surrounding the magmatic source calculating the temperature distribution by a thermo-mechanical numerical model. Secondly, we included around the pressurized magma source an elasto-plastic zone, whose dimension is related to the temperature distribution. This elasto-plastic model gave rise to deformation comparable with that obtained from elastic and viscoelastic models, but requiring a geologically satisfactory pressure. We successfully applied the method to review the ground deformation accompanying the 1993–1997 inflation period on Mt Etna. The model considerably reduces the pressure of a magma chamber to a few tens of MPa to produce the observed surface deformation. Results suggest that the approach presented here can lead to more accurate interpretations and inferences in future modeling-based assessments of volcano deformation.