3D integrated geophysical modeling for the 2008 magma intrusion at Etna: Constraints on rheology and dike overpressure

摘要

We present a 3D numerical model based on Finite Element Method (FEM) to jointly evaluate geophysical changes caused by dislocation and overpressure sources in volcanic areas. A coupled numerical problem was solved to estimate ground deformation, gravity and magnetic changes produced by stress redistribution accompanying magma migration within the volcano edifice. We successfully applied the integrated numerical procedure to image the magmatic intrusion occurring in the northern flank of Etna during the onset of the 2008 eruption. A multi-layered crustal structure of the volcano constrained by geological models and geophysical data was considered. Geodetic and gravity data provide information on the strain field, while piezomagnetic changes give constraints on the stress field. Therefore, the integrated modeling gives insights on Mt Etna rheology and dike overpressure involved in the magma propagation and improves understanding of dike emplacement in the northern sector of the volcano. Our FEM-based approach improves the reliability of model-based inference of geophysical parameters obtained during monitoring of the onset of Etna lateral intrusions that can prelude to an impending eruption.