New Constraints Into the Present day Kinematics of the African/Eurasian Plate Boundary System From the Analysis of Permanent and Non-Permanent GPS Data

The Mediterranean area is presently characterized by a relatively high number of crustal wedges behaving independently or partially independently with respect to one another, as consequences of a complex space and time evolution of the African/Eurasian plate boundary system. This work concerns the analysis of continuous and non-continuous GPS data collected in the Mediterranean region, and in particular in the Adriatic/Tyrrhenian domain, in order to tentatively constrain the kinematics of crustal blocks and the distribution of geodetic strain rates. The structural complexity of the Mediterranean and its relatively low deformation rates ask for a high number of GPS stations with very high precision and long observation time spans. In this work we improve the space and time resolutions of the available GPS data combining both permanent and geophysical dedicated non-permanent networks, providing significant information to better constrain the complex deformation pattern of this high tectonically fragmented zone. Continuous GPS data for the time span 1998-2002, collected on stations managed by different Italian and European institutions, have been processed and combined with survey mode GPS data, collected on different geodetic networks in the time span 1991-2001. The whole data set has been analyzed following a uniform processing strategy, by means of the distributed session approach, and using each individual daily solution in terms of quasi-observations for a position time series analysis and the evaluation of crustal motions. The final velocity field has been used to evaluate a stable European frame, which significantly differs from the NNR-NUVEL-1A. An analysis in terms of rigid-block motions has been performed and a kinematic interpretation has been carried out, delineating some "first order" crustal wedges. The long wavelength geodetic strain rate field has been computed in order to obtain a smoothed picture of the higher strain concentrations zones, which seems to be the Aegean area, the Calabrian arc and the central-southern Apennines.