Imaging Crustal Structure of the Transition between Zagros Collision and Makran Subduction using Events Interferometry Approach

Convergence between the Arabian and Eurasian plates leads to a continental collision zone in western Iran (along the Zagros Collision) and a subduction zone in southern Iran (along the Makran Subduction). We obtained shear wave velocity (V_S) model for collision-subduction transition zone, which is characterized by Minab-Zendan-Palami (MZP) fault, using event-pair interferometry method. We used 630 vertical components of earthquakes (M_W≥4) recorded by the Iranian Seismological Center (IrSC) network. The dataset has been collected from 107 stations from January 2006 to May 2019. We removed the mean, trend, and instrument response and performed pre-processing filtering in the period range of 4 - 26 s. By cross-correlation of the prepared signals and then using phase weighted stacking procedure, the signal to noise ratio (SNR) of retrieved EGFs was enhanced. We then calculated group velocity of Rayleigh wave dispersion curves. Finally, an iterative damped least square inversion was performed to obtain the V_S model of the collision-subduction transition zone in the south of Iran. The V_S model represents that a low velocity anomaly with a 30 km width, which is extended along the MZP fault, could remark the transition zone.