Kinematics of the Kahramanmaraş triple junction and of Cyprus: evidence of shear partitioning

Abstract

Triple junctions involving non-subductable plates extend beyond local implications, crucial for studying the geology of convergent plate boundary zones. However, kinematic models overlook Cyprus-Anatolia motion due to limited geodetic constraints. Our study area comprises Cyprus, southern Turkey, and the Levant coast, focusing on the Kahramanmaraş triple junction where a destructive earthquake sequence occurred on February 6, 2023. We present precise positioning data merged with published velocities, constructing an up-to-date velocity field for the interseismic period. Employing two kinematic approaches, we analyze its tectonic implications. In Cyprus, we find the relative motion of Africa (Sinai Plate) and Anatolia is partitioned between convergence in the Cyprus subduction, with rate 3.5-6.2 mm/yr, progressively decreasing from west to east and left-lateral transpressive Kyrenia fault, situated along the northern coast of Cyprus, with rate 3.3-4.2 mm/yr. The relative strike-slip motion between Arabia and Anatolia is partitioned between the East Anatolian Fault (slip rates 5.2-6.2 mm/yr) and some secondary faults such as Çardak and Malatya faults (slip rates 2.0-1.7 mm/yr respectively) and causes distributed deformation for a 50-60 km wide region. The largest second invariant strain rate tensors from the continuum kinematic model also coincide with the same region which can be defined as the East Anatolian shear zone. A shear partitioning system exists around the Kahramanmaraş triple junction, from Cyprus to southeast Turkey. The Levant Fault has a 3.5-4.7 mm/yr left-lateral slip rate, decreasing northward as part of it is transferred to offshore faults. Strain rates appear to be relatively small in the Taurus range and Adana/Cilicia basin, transitioning from extensional/transtensional to compressional from east to west. The up component of GNSS velocities on the Taurus karstic plateau reaches 1.2 mm/yr, lower than Quaternary uplift rates on its southern edge. We examine Taurus uplift and Adana/Cilicia basin subsidence, considering slow convergence through earthquake distribution, seismic tomography, and modeling.