Moho depth variations and Vp/Vs ratio in the Zagros (Iran) from teleseismic converted waves

Abstract

Variation of Moho depth and Vp/Vs ratio beneath the Zagros using 3 years of teleseismic recording at twenty permanent broadband seismic stations of the Iranian Seismological Center (IRSC) where are scattered all over Zagros is presented in this paper. The results of this study are the first receiver function study for the Moho depth beneath these stations on this new dataset. We determine receiver functions by the time domain iterative deconvolution method and Moho depth and Vp/Vs ratio using a modified Zhu and Kanamori method. Our results indicate that the Moho depth beneath the Zagros Mountain Range varies from ~ 30–35 km in western Zagros near the Arabian platform, up to ~ 45 km beneath Central Zagros. In the main Zagros zone, our results indicate a uniform pattern for the Moho depth. The Moho depth reaches ~ 50–54 km beneath stations near Sanandaj-Sirjan Zone (SSZ), indicating a considerable increase of Moho depth from the west toward the east of Zagros. The depth of Moho in the southeast of Zagros is less than other parts of Zagros. We found deepening of the Moho depths beneath stations near the SSZ which can be due to the overthrusting of the crust of Zagros by the crust of central Iran along the MZT. The average Vp/Vs ratio in Zagros is 1.8.