3D numerical deformation model of the intrusive event forerunning the 2001 Etna eruption

3D finite elements models were carried out in order to evaluate the ground deformation produced by
the dike intrusion occurred at Etna volcano in the 2001. The finite element method (FEM) allows for
considering the medium heterogeneity and the real topography of the volcano. Firstly, we validated the
method in ahomogeneous elastic half-space andcompared the results with those obtained fromanalytical
dislocation models. We performed a convergence analysis to quantify the discretization errors, which
are sensitive to the size and quality of the mesh elements and can cause inaccurate numerical solutions.
Secondly, several numerical modelswere conducted to appreciate howthe complex distribution of elastic
medium parameters and the topography make the numerical results differ from the simple analytical
solutions. The numerical model, which account for the real topography of Etna volcano and medium
heterogeneity, well match the ground deformation observed at the GPS stations between 11 and 16 July
2001. It appears that topography and heterogeneities provide more details about the ground deformation
near the summit crater area that are missed when homogeneous half-space models are used. However,
only fewdiscrepancies between the analytical and the numerical models are observed at the GPS stations,
which coarsely sample the volcanic edifice far away from the summit craters.