Toward a realistic deformation model of the 2008 magmatic intrusion at Etna from combined DInSAR and GPS observations

The combination of (i) DInSAR data, capable of observing deformation pattern at a spatial resolution unachievable with other sparse geodetic measurements, (ii) continuous GPS data, able to provide temporal constraints on source evolution, and (iii) numerical modeling procedures, appropriate to consider a non-uniform opening distribution of a source embedded in a 3D heterogeneous medium, allowed us to infer a complex and realistic deformation model of the magmatic intrusion that occurred in the northern flank of Etna on 13 May 2008. Numerical modeling of ground deformation data defines a near-vertical dyke intruded for 2.5 km starting from a depth of 1400 m asl right below the summit craters and reaching shallow crust level in the northern flank. From the estimated opening distribution of the propagating magma-filled crack, which reached a maximum value of about 2 m, a volumetric expansion of crustal rocks of about 5.3 × 106 m3 was obtained. Also, we clarified the temporal evolution of the northward magmatic intrusion, which lasted just over 5 h with an initial magma propagation velocity of about 1.2 km/h, and decreased to about 0.24 km/h as the driving pressure lowered due to the effusive activity started at southern vents.

► We define magma intrusion scenario at the onset of the 2008 Etna eruption.
► InSAR and GPS data constrain spatial extent and temporal evolution of the intrusion.
► Opening distributions of magma-filled crack are derived in a 3D FE model.
► We provide a reliable modeling-based assessment of the volcanic hazard.