Finite element modeling of ground deformation and gravity field at Mt. Etna

Abstract

An elastic 3-D axi-symmetric model based on Finite Element Method (FEM) is proposed to compute ground deformation
and gravity changes caused by overpressure sources in volcanic areas. The numerical computations
are focused on the modeling of a complex description of Mt Etna in order to evaluate the effect of topography,
medium heterogeneities and source geometries. Both ground deformation and gravity changes are investigated
by solving a coupled numerical problem considering a simplified ground surface profile and a multi-layered
crustal structure inferred from seismic tomography. The role of the source geometry is also explored taking into
account spherical and ellipsoidal volumetric sources. The comparison between numerical results and those
predicted by analytical solutions disclosed significant discrepancies. These differences constrain the applicability
of simple spherical source and homogeneous half-space hypotheses, which are usually implicitly assumed
when analytical solutions are applied.