Present-day kinematics of the Mediterranean: A comprehensive overview of GPS results
Résumé
I combine recently published GPS results to derive a geodetic horizontal velocity field consistent at the scale of the Mediterranean and the surrounding Alpine belts. The velocity field is then used to discuss the boundary conditions around each major deforming area in the Mediterranean, to describe the main patterns of motion and deformation, to critically review the existing kinematics models and to finally point out the main unresolved kinematics questions. Strain rate in Europe north of the Alpines belt is dominated by the signature of the Glacial Isostatic Adjustment and tectonic strain remains below the current accuracy of GPS results. In the western Mediterranean, deformation is restricted to the Betics, the Alboran and the Morrocan Rif, with west-to-southwestward motion with respect to Iberia, which is part of stable Europe. Shortening, consistent with the relative Nubia/Eurasia plate motion, is found throughout the Maghrebides, but the distribution of deformation in northern Africa remains largely unknown. The central Mediterranean is dominated by the counter-clockwise rotation of the Adriatic. The junction between the southern Adriatic domain and Nubia has yet to be firmly established. The deformation over a wide area, east of the Maghrebides, in Tunisia and the gulf of Sirte in Libya still remains to be quantified. In the eastern Mediterranean, the velocity field is dominated by a general anti-clockwise rotation and a general trend towards the Hellenic trench, with velocity magnitude increasing with decreasing distances from the trench. This trend is observed not only in the Aegean and Anatolia, but also in the southern Balkans. Geodetic results emphasize that the convergence of the Nubia and Arabia plates towards Eurasia directly controls the deformation across only very few segments along the plate boundary zone. Additional processes are therefore required to explain the observed velocity field and deformation pattern.