Satellite Geodesy and Geodynamics

The geodynamic processes in the Mediterranean area are reflected in the recent crustal movements determined by satellite geodesy. There is a counterclockwise rotation of Africa relative to Eurasia, with complex deformation in between. A key feature to a better understanding of the driving forces and associated seismic activity in the Africa/Eurasia collision zone is the Hellenic Arc. This thesis reports on repeated GPS measurements, that began in 1989, along the western coast of Greece (including some stations in southern Italy). The results are presented in terms of relative displacements and strain rates. They reveal distinct crustal motion of the central Ionian Islands and SW Greece: Over a time span of five years various parts of Greece have moved to the SW at a rate of -40 mm/a relative to SE Italy and Epiros. The trajectories constructed from the repeated observations show that the boundary zone, against the sites of no significant motion relative to South Italy, coincides with the Kephalonia fault zone (KFZ) where a maximum of strain energy density was also found. The maximum strain rate is 0.18 (istrain/a, located in the vicinity of Lefkada where anomalously high earthquake activity is observed. This intense deformation accounts for the earthquakes that have frequently devastated the Central Ionian Islands. The deformation field of the KFZ is interpreted as a transition zone between the kinematics of the Eurasian and the Aegean/Anatolian plates (Hellenic fold and thrust belts). Seismic risk assessment is one important application of geodetically-determined strain rates. This thesis also includes an approach for approximating the observed displacement field by the use of a tectonic model for the area of investigation.