Moho depth variations and Vp/Vs ratios in the seismotectonic zones of Central Iran, Eastern Iran, and Makran: using a modified Zhu and Kanamori method

Abstract

Variations of the Moho depth and Vp/Vs ratio beneath the Central Iran, Eastern Iran, and Makran regions using a modified Zhu and Kanamori method are presented in this paper. Receiver functions have been calculated from 3 years of teleseismic recordings at seventeen broadband stations using a time-domain iterative deconvolution method. Our results indicate that Moho depth changes from 56 km beneath the western part of Central Iran to 40 km in Central Iran and 38 km in Eastern Iran. The relatively thick crust beneath western margin of Central Iran is due to the close proximity of this region to the Sanandaj-Sirjan Zone and the Urumieh-Dokhtar magmatic arc that are associated with underthrusting of the Arabian plate beneath Central Zagros along the main Zagros reverse fault. Also, crustal thickening of this region would be due to volcanic intrusions, magmatic. The reduction of crustal thickness beneath the eastern stations in this region could be due to the absence of a collisional zone in the tectonic evolution of the region. The results beneath the CHBR station located in Makran indicate a value of 31 km for crustal thickness and 1.70 for the Vp/Vs ratio. It is associated to subduction of the oceanic crust of the Arabian plates, beneath the southern part of the Makran crust with a very low slope. The crust beneath Central and Eastern Iran has a moderate thickness which decreases from west to east.