Magmatic and tectonic sources at Vulcano (Aeolian Islands, Southern Italy): a geodetic model based on two decades of GPS observations

An update of the surface ground deformation field over the Lipari-Vulcano complex has been provided by analyzing all the available GPS observations collected in the last two decades. The geodetic velocity field, referred to a fixed Eurasian frame, shows a remarkable negative velocity gradient between the southernmost stations (velocity values of ∼9.0 mm/yr) and the northernmost ones, resulting in a N–S contraction of ∼4.5 mm/yr. In addition, all the GPS stations show subsidence with rates decreasing from the northernmost stations (∼ -10.0 mm/yr) to the southernmost ones (∼ -4.8 mm/yr). Modelling of geodetic data demonstrates that the observed surface deformation field results from the joint contribution of regional (tectonic) and local (magmatic) sources. Such a dataset is unable to uniquely constrain the magmatic source. Indeed, the three performed models (M1, M2 and M3) produce statistically equivalent deformation sources. The source modeled in M1 is spatially coincident with that of M3, and both are located beneath the Vulcanello cone at depth of ∼4 km bsl. Conversely, the source modeled in M2 is placed at depth of 0.76 km bsl beneath the northern rim of the La Fossa crater. Integration of these results with geochemical and petrological data already available from literature suggests, however, that the M1≡M3 source placed beneath the Vulcanello cone should be the preferred model.