[S-CG55] Dynamics in mobile belts

[SCG55-11] Tectonic deformation of the Aegean Sea due to the slip of the North Anatolian Fault and the Hellenic subduction

*Akinori Hashima¹, Tülay Kaya Eken², Haluk Özener² (1.Tokyo Gakugei University, 2.Department of Geodesy, Kandilli Observatory and Earthquake Research Institute, Bogazici University)

Keywords:Kinematic subduction model, GPS, Inversion, Hellenic trench, North Anatolian fault

The Aegean Sea and the neighboring Anatolian Peninsula, located between the Eurasia, Africa, and Arabian plates, constitute one of the most active tectonic regions of the world. The tectonic mechanism/structure in this region is considered to be controlled by the subduction of the African plate beneath the Hellenic trench and the movement of the North Anatolian Fault Zone (NAFZ). The Aegean Sea between Peloponnese and Anatolian Peninsulas is under the North-South extensional regime and hosts normal fault earthquakes such as the 2020 Mw7.0 Samos earthquake. A rational assessment of the seismic risk in this region requires a unified understanding of surface deformation, stress loading, and process of crustal structure formation due to the Hellenic subduction and the NAFZ movement. To quantitatively separate these two contributions, we analyze published GPS data in the Greece–Türkiye region. We assume a simple elastic–viscoelastic layered earth for the structure model of this region. In the first step of the analysis, we compute deformation rates at the GPS stations due to the uniform slip rates on the NAFZ. We subtract the computed deformation rates from the observed GPS velocities. Then, we apply slip inversion on the residual deformation rates to obtain slip distribution under the Hellenic trench. Our optimum model shows <35 mm/yr slip rate at the NAFZ and average ~40 mm/yr slab rollback rate under the Hellenic trench. Our results suggest the equal contributions of the Hellenic slab rollback and the NAFZ movement on the deformation of the Aegean Sea.