Dynamics of Mount Etna Volcano inferred from static and kinematic GPS measurements

Ground deformations measured on Mount Etna from late 1995 to mid-1998 using GPS observations are analyzed. Four GPS surveys were carried out during the considered period. In 1995 the GPS network consisted of 18 stations on the volcanic edifice and 6 stations around it. During the 1996 survey, 22 new monuments were added along a N-S profile crossing the summit craters area. This profile was surveyed by a semikinematic method, allowing greater spatial detail to be achieved on the uppermost part of the volcano. The comparisons between the GPS surveys are reported here in terms of horizontal and vertical displacements for each station and also in terms of areal dilatation and strain distribution. This last parameter continues its ascending trend, at a rate of ~5 μstrain yr−1, already shown in the previous period, after the end of the 1991–1993 flank eruption. Inversion of the ground deformation patterns permits investigation of the evolution of both the position and dynamics of magma reservoirs beneath the volcano, consistently associated with a general eastward sliding of its eastern sector. This study allows us to define the nonuniqueness of ground deformation sources through the investigated period, suggesting that the plumbing system of the volcano is made up of a complex system of single intrusions occurring at different times