ACTIVE TECTONICS OF TURKEY AND SURROUNDINGS: A SYNTHESIS OF SOURCE PARAMETERS AND RUPTURE HISTORIES OF RECENT EARTHQUAKES

The complexity of plate interactions and associated crustal deformation in the eastern Mediterranean region is marked by the occurence of many destructive earthquakes throughout the recorded history. The Aegean region, including western Turkey and Greece, is indeed one of the most seismically active and rapidly deforming continental domains in the Earth. The wide range of deformational processes occurring in this region means that the eastern Mediterranean provides a unique opportunity to improve our understanding of the complex kinematics of continental collision, including strike-slip faulting and crustal extension, as well as associated seismicity and volcanism. The tectonic evolution of the Eastern Mediterranean region is dominated by effects of subduction along the Hellenic (Aegean) arc and of continental collision in eastern Anatolia and the Caucasus. Northward subduction of the African plate beneath western Anatolia and the Aegean region is causing crustal extension in the overlying Aegean province. Eastern Anatolia is instead experiencing crustal shortening and thickening due to northward motion of the Arabian plate relative to Eurasia. The resulting combination of forces: the “pull” from the subduction zone to the west and “push” from the convergent zone to the east, is causing the Turkish plate to move westward, bounded by strike-slip fault zones: the North Anatolian Fault Zone (NAFZ) to the north and the East Anatolian Fault Zone (EAFZ) to the south. The interplay between dynamic effects of the relative motions of adjoining plates thus controls large-scale crustal deformation and the associated earthquake activity in Turkey.

We have studied source mechanisms and rupture histories of ~100 earthquakes using body-waveform modelling, and have compared the shapes and amplitudes of teleseismic long-period P-, SH-, and broadband P-waveforms recorded by GDSN stations in the distance range of 30–90º. They all exhibit the characteristics and structural complexities associated with strike-slip, thrust and normal faulting as a result of ongoing crustal deformation.