Seismic response to volcanic processes at Mount Etna: coupling thermomechanical simulations with seismic wave-equation modeling

Mt. Etna, located in the north-eastern area of Sicily (Italy), is one of the most active and hazardous strato-volcano in the world, both in terms of paroxysmal events and continuous effusive activity from the summit area and hazardous flank eruptions. Long-term processes of deep magma recharge and storage within the upper crust, passive magma ascent along pre-existing weaknesses, and forceful dyke intrusions allow magma to rise to the surface. Past studies provided evidence supporting the view that the interplay between magma dynamics and storage and the thermomechanical response of the host medium control magma rise and the brittle seismic response of the volcano basement and edifice.

To further investigate this interplay, we have performed 3D thermomechanical simulations of the present-day state of the volcano using the Lithosphere and Mantle Evolution Model (LaMEM) code. The model is built between the volcanic surface and 30km depth and includes realistic topography. Magma storage zones within the model are inferred from seismic tomography and seismic source studies at ~30km (deep storage) and between 3 and 6 km (shallow storage). The characteristics of the molten zones are calibrated by physical and mechanical properties determined for the main representative lithologies (carbonates, basalts, clays) and the corresponding rheological laws. As we are interested in the present-day dynamics of the volcano, we ran our models for just a few timesteps to gain surface velocity and displacement data.

The LaMEM framework allows retrieving both deformation and gravity responses to the final model. These responses will be fit to real GPS, InSAR, and gravity data to define the most realistic properties of the Etna feeding systems. Future steps will include tectonic forces contributing to the sliding of the eastern volcanic flank in the simulation and propagation of seismic waves in the final model suitable to fit existing seismic data.