Dynamics of Mt. Etna before, during and after the 2001 eruption, inferred from GPS and DInSAR data.
Giuseppe Puglisi(1) , Alessandro Bonforte(1)
, Alessandro Ferretti(2)
, Francesco Guglielmino(1)
, Mimmo Palano(1)
, and Claudio Prati(3)
Ist. Naz. Geofisica e Vulcanologia,
Piazza Roma, 2,
(2) Tele-Rilevamento Europa - T.R.E. s.r.l., V. Colonna, 7, 20149 Milano, Italy
(3) Politecnico di Milano, V. Ponzio 34/5, 20133 Milano, Italy
The ground deformation data encompassing the 2001 Mt. Etna eruption are analyzed by using both GPS and DInSAR techniques. Five ERS-2 ascending passes and three descending ones are used to form five DInSAR pairs spanning from 1 month to 1 year periods, before and during the 2001 eruption. Five GPS surveys are considered in this work. They were carried out from July 2000 to October 2001 on the entire Mt. Etna network or on its southeastern part. The measurement on the entire Mt. Etna network provided information on ground deformation pattern of the whole volcano, while the southern sub-network provides detailed ground deformation pattern produced by seismic crises in January and October 2001. Inversions of the GPS 3D sparse ground deformation data, refined by the 1D but continuous above the volcano DInSAR data, were performed to obtain theoretical models for pre-eruptive, syn-eruptive and post-eruptive periods.
The modeled framework depicts a pressure source located at about 6 km b.s.l. inflating before the eruption that drastically depressurized during and after it. The intrusion of a N-S dyke in the central part of the volcano strongly affects the ground deformation field in all comparisons encompassing the eruption. The sliding motion of the eastern flank of the volcano characterizes all the time intervals analyzed and the geometry of the sliding plane has been better defined with respect to previous studies. The sliding motion abruptly accelerated with the dyke intrusion and this acceleration continued after the end of the eruption. The acceleration was accompanied by the propagation of the strain field towards the eastern periphery of the volcano, revealed by the activity of the NNW-SSE “Timpe” faults.