Kinematics of the Kahramanmaraş triple junction: evidence of shear partitioning

Abstract

Triple junctions involving convergent plate boundaries extend beyond local implications, which is crucial for studying the geology of convergent plate boundary zones. However, kinematic models overlook Cyprus-Anatolia mo- tion due to limited geodetic constraints. Our study area comprises Cyprus, southern Turkey, and the Levant coast, focusing on the Kahramanmara ̧s triple junction, where a destructive earthquake sequence occurred on Febru- ary 6, 2023. We present precise positioning data merged with published ve-locities, 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 a rate of 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 C ̧ardak 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, the East Anatolian shear zone. A shear partitioning system exists around the Kahramanmara ̧s 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 relatively small in the Taurus range and Adana/Cilicia basin, transitioning from ex- tensional/transtensional to compressional from east to west.