Ductile Versus Brittle Tectonics in the Anatolian–Aegean–Balkan System

It is hypothesized that the present tectonic setting of the Anatolian, Aegean and Balkan regions has been deeply influenced by the different deformation styles of the inner and outer belts which constituted the Oligocene Tethyan system. Stressed by the Arabian indenter, this buoyant structure has undergone a westward escape and strong bending. The available evidence suggests that in the Plio–Pleistocene time frame, the inner metamorphic core mainly deformed without undergoing major fragmentations, whereas the orogenic belts which flanked that core (Pontides, Balkanides, Dinarides and Hellenides) behaved as mainly brittle structures, undergoing marked fractures and fragmentations. This view can plausibly explain the formation of the Eastern (Crete–Rhodes) and Western (Peloponnesus) Hellenic Arcs, the peculiar time-space features of the Cretan basins, the development of the Cyprus Arc, the North Aegean strike-slip fault system, the southward escapes of the Antalya and Peloponnesus wedges and the complex tectonic setting in the Balkan zone. These tectonic processes have mostly developed since the late Late Miocene, in response to the collision of the Tethyan belt with the Adriatic continental domain, which accelerated the southward bending of the Anatolian and Aegean sectors, at the expense of the Levantine and Ionian oceanic domains. The proposed interpretation may help us to understand the connection between the ongoing tectonic processes and the spatio-temporal distribution of major earthquakes, increasing the chances of estimating the long-term seismic hazard in the study area. In particular, it is suggested that seismic activity in the Serbo–Macedonian zone may be favored by the post-seismic relaxation that develops after seismic crises in the Epirus thrust front and inhibited/delayed by the activations of the North Anatolian fault system.