Ground deformation modeling of flank dynamics prior to the 2002 eruption of Mt. Etna

On 22 September 2002, 1 month before the
beginning of the flank eruption on the NE Rift, an M-3.7
earthquake struck the northeastern part of Mt. Etna, on the
westernmost part of the Pernicana fault. In order to
investigate the ground deformation pattern associated with
this event, a multi-disciplinary approach is presented here.
Just after the earthquake, specific GPS surveys were carried
out on two small sub-networks, aimed at monitoring the
eastern part of the Pernicana fault, and some baselines
belonging to the northeastern EDM monitoring network of
Mt. Etna were measured. The leveling route on the
northeastern flank of the volcano was also surveyed.
Furthermore, an investigation using SAR interferometry
was performed and also the continuous tilt data recorded at
a high precision sensor close to the epicenter were analyzed
to constrain the coseismic deformation. The results of the
geodetic surveys show a ground deformation pattern that
affects the entire northeastern flank of the volcano, clearly
shaped by the Pernicana fault, but too strong and wide to be
related only to an M-3.7 earthquake. Leveling and DInSAR
data highlight a local strong subsidence, up to 7 cm, close
to the Pernicana fault. Significant displacements, up to
2 cm, were also detected on the upper part of the NE Rift
and in the summit craters area, while the displacements decrease at lower altitude, suggesting that the dislocation
did not continue further eastward. Three-dimensional GPS
data inversions have been attempted in order to model the
ground deformation source and its relationship with the
volcano plumbing system. The model has also been
constrained by vertical displacements measured by the
leveling survey and by the deformation map obtained by
SAR interferometry.

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