Fault-plane Solutions Determined by Waveform Modeling Confirm Tectonic Collision in the Eastern Adriatic

Abstract

— Source parameters for thirteen earthquakes in the SE Adriatic region have been determined using P and SH body-waveform inversion. The results of this modeling are combined with eleven other earthquakes with M ≥ 5 whose focal mechanisms have been determined mainly by waveform modeling. The results confirm that movement on mainly low-angle reverse faults causes the deformation in coastal southern Yugoslavia through Albania up to the Lefkada Island in NW Greece. This zone of thrusting has a NW–SE trend (N34°W), follows the coastline, and dips towards the continent. The slip vectors of these events trend at ∼N229° along the Dalmatian coasts, to ∼N247° along Albania and NW Greece. The deformation is attributed to the continental collision between the Adriatic block to the west and Eurasia to the east. Along the mountain line in eastern Albania (Albanides Mts.) and in NW Greece (Hellenides Mts.), E–W extension is occurring. The E–W extension associated with the orogenic belt could be attributed to a variety of models such as: gravity, internal deformation of the thrust wedge, a probable down bulge of the dense lithosphere of the Adriatic block beneath the Eurasian lithospheric plate in combination with the compressional stresses applied along the collision belt.