The Hellenic subduction and the tectonics of the 2023 earthquakes of SE Anatolia

Two very strong earthquakes and many aftershocks spread havoc in southeast Turkey in February 2023, and indeed southeast Anatolia is an intricate geological region where two tectonic processes coincide, creating a complicated setting of the motion of the crustal blocks of the Levant and Anatolia and generating strong seismic activity. GPS measurements show clearly that not only does Anatolia move westwards, but that the velocity of that displacement increases westwards from ca. 20 mm/year to more than 30 mm/year. Furthermore, in the Aegean domain the offset changes its direction to southwest and its velocity continues to increase. It seems that the tectonic cause of Anatolia's westwards migration is the rollback of the Hellenic subduction front, which exerts a significant on the entire Anatolian crustal block. Geological and geophysical evidence for that pull is abundant throughout the Aegean domain. The Anatolian migration is accommodated along its large boundary faults, the North and East Anatolian Faults, which are very active seismically and converge in eastern Anatolia near Karliova.

The tectonics of the Levant is dominated by the Levant (Dead Sea) Rift and its mountainous flanks and oblique extension, where the left-lateral displacement along it is ca. 5 mm/yr. The tectonic regime there is dominated by the northwards propagation of the edge of the Red Sea incipient ocean, which changes its direction of advancement from northwestwards to northwards south of Sinai Peninsula. It seems that the Levant Rift ends its northwards propagation in north Lebanon, where its orientation shifts to the NE and the large fault is split into at least five secondary faults, and ends with the north edge of the Lebanese Baqa'a and its double mountain chains.

The tectonics of the terrain between the Lebanese mountainous domain and the East Anatolian Fault is controversial. Many researchers propose linkage of the Levant Rift and the East Anatolian Fault, which are both sinistral fault systems, by connecting the Yammouneh Fault, one of the Lebanese faults splay, with Masyaf Fault, a southwards extension of the East Anatolian Fault, and the eastern boundary of El-Ghab Rift.

Overall, it seems that the complex structural geology of the domain of eastern Anatolia and northern Levant reflects the complicated tectonics of the closure of NeoTethys Seaway, where the convergence of the Arabian segment of the African and the Eurasian tectonic plates take place. The eastern branch of the Seaway evolved into a collision zone between Arabia and the Bitlis-Zagros mountain belt, whereas subduction still prevails along the western NeoTethys between Africa and Europe. While the old ocean approaches its terminal stages, a new ocean is emerging in the Red Sea. The tectonic displacements indicate that the concept of "escape tectonics" seems poorly supported.