Implementing GALES, a multiphysics Finite Element software, to model magma replenishment dynamics and associated Ultra-Long Period deformation patterns and tilt at Mount Etna

Numerical simulations of magma dynamics have revealed that Ultra-Long Period (ULP) ground displacements can be attributed to deep magma convection. This research produces a series of one-way coupled, time-dependent models of magma and rock dynamics during multicomponent magma convection and mixing are simulated in different chamber-dyke systems using a multiphysics finite element software, GALES (Garg et al., Comp. Math. Appl., 2021).

Modelled firstly by simulating 2D magma mixing during a replenishment scenario whereby magmas of variable compositions and temperatures are free to interact at an interface, the properties of which were constrained using the estimated saturation conditions of melt inclusions. The overpressures at the fluid-solid interface are then imposed as a boundary condition to simulate the elastostatic response of the surrounding medium. These 2D models were then extended and embedded into a 3D domain (Longo), with dimensions of 100 x 100 km and a depth of 50 km, that accounts for topography, the heterogeneous rock property profile (seismic tomography data) and incorporates the INGV’s multiparametic stations on the surface. 

This setup not only aided in constraining the characteristics of the Mount Etna volcanic system but also enabled the derivation of detailed synthetic space-time series of ground deformation at each of the stations for each of the pre-defined chamber geometries. Analysis of these respective synthetic signals reveal oscillations in a period range of approximately 150-300 seconds and changes in tilt in the order of milliradiants. 

Direct comparisons with recorded tilt measurements, obtained on Mount Etna as part of IMPROVE’s multiparametric experiment in July 2023, can potentially identify sets of geophysical signals that are diagnostic of magma movements at depth and help develop our interpretation of the dynamics between storage regions throughout the volcanic system and their overall contributions to the resultant deformation patterns.