Intrusive mechanism of the 2002 NE-rift eruption at Mt Etna (Italy) modelled using GPS and gravity data

Abstract

Microgravity and GPS data collected at Mt Etna during a 1-yr time interval encompassing the 2002 NE-rift eruption are analysed. The common GPS-gravity profile traverses the summit area of Mt Etna, between the summit craters (about 3000 m) and the northernmost tip of the eruptive fractures (2500 m). Displacements (up to 2 m in both the horizontal and vertical directions) and gravity variations (up to 350 mu Gal, after having removed the effect of elevation changes) observed during this period are among the largest ever recorded at Etna. Displacements and gravity changes have been modelled separately, assuming a magma influx from the summit feeder pipe to the NE-rift. Models obtained through surface deformation data partially overlap with those explaining the gravity data but in general are narrower and extend to a greater depth. The discrepancies found between gravity and deformation models are significant and can be regarded as due to the different structural features encountered by the intruding magma during its downslope propagation along the NE-rift. In particular, on the grounds of our result, we infer that both the eastward sliding of the east flank of the volcano and the curved shape of the NE-rift influenced the 2002 intrusive process.