Autori: Gilda Currenti, Giuseppe Solaro, Rosalba Napoli, Antonio Pepe, Alessandro Bonaccorso,
Ciro Del Negro, Eugenio Sansosti.
In audio la ricercatrice Gilda Currenti
We investigate the displacement induced by the 2–3 April 2010 seismic swarm (the largest event being of Ml
4.3 magnitude) by means of DInSAR data acquired over the volcano by the Cosmo-SkyMed and ALOS radar
systems. Satellite observations, combined with leveling data, allowed us to perform a high-resolution modeling
inversion capable of fully capturing the deformation pattern and identifying the mechanism responsible
for the PFS seismic activation. The inversion results well explain high gradients in the radar line of sight displacements
observed along the fault rupture. The slip distribution model indicates that the fault was characterized
by a prevailing left-lateral and normal dip–slip motion with no fault dilation and, hence, excludes that
the April 2010 seismic swarm is a response to accommodate the stress change induced by magma intrusions,
but it is due to the tectonic loading possibly associated with sliding of the eastern flank of the volcano edifice.
These results provide a completely different scenario from that derived for the 22 September 2002 M3.7
earthquake along the PFS, where the co-seismic shear-rupture was accompanied by a tensile mechanism
associated with a first attempt of magma intrusion that preceded the lateral eruption occurred here a
month later. These two opposite cases provide hints into the behavior of the PFS between quiescence and unrest
periods at Etna and pose different implications for eruptive activity prediction and volcano hazard assessment.
The dense pattern of ground deformation provided by integration of data from short revisiting
time satellite missions, together with refined modeling for fault slip distribution, can be exploited at different
volcanic sites, where the activity is controlled by volcano-tectonic interaction processes, for a timely evaluation
of the impending hazards.