Insights into present-day crustal motion in the central Mediterranean area from GPS surveys

SUMMAR YIn this paper we present observations of crustal motion related to a large GPS network located in the central-western Mediterranean area.Velocities are obtained by the analysis of more than 30 observing sites at which at least three different GPS campaigns were carried out in the time span 1991-1999.The results are presented both in the ITRF96 reference frame and with respect to a Eurasian fixed reference frame.The sites located along the northern African margin, in Sicily and southern Italy show prevalent northeastward movements with a mean velocity of roughly 0.7 cm yr x1 .The relatively dense network available in the southern Apennines led us to try a tentative estimate of the average strain rate in this zone, resulting in a maximum extension of 0.021t0.006r10x6 yr x1 normal to the chain.In Ionian Greece the two sites located south of the Kephallinia discontinuity (Lefkas and Kastro Ilias) consistently indicate a south to southwestward motion at an average rate of roughly 15 mm yr x1 .