PLATE TECTONIC FRAMEWORK AND GPSDERIVED STRAIN-RATE FIELD WITHIN THE BOUNDARY ZONES OF THE EURASIAN AND AFRICAN PLATES

Abstract

The Adriatic microplate forms the central pail of the Alpine-Mediterranean plate boundary area located between the African and Eurasian Plates. The Eurasia/Africa collision is closely related to continental subduction. Superimposed on the relatively slow counterclockwise rotation of the African Plate, complex dynamic processes affect lithospheric blocks between the two major plates. Seismic results indicate the presence of subducted lithosphere below the Alpine-Mediterranean collision belt. The belt displays pronounced differences in structural style. Compressional deformation and mountain building can be traced around the Adriatic block including the Calabrian and Hellenic arcs. Recent GPS results reveal large motion for the Anatolian/Aegean microplates directed towards west-southwest, relative to the Eurasian Plate. In the Calabrian Arc and Ionian Sea area, there is a complex distribution of compressional and tensional stress regimes. Most recent GPS results indicate a relatively strong compressional strain regime to the north of Sicily, which is concordant with fault-plane solutions of recent earthquakes and which is indicative of the position of the actual kinematic boundary of the African Plate. The Tyrrhenian Sea and its surroundings move like the Eurasian Plate. The boundaries of the Anatolian/Aegean Plates are characterized by large strain rates due to rapid W-SW oriented movement that reaches 35 mm/y.