Continental Lithosphere Structure Beneath the Iranian plateau, from Analysis of Receiver Functions and Surface Waves Dispersion

Abstract eng:
More than one year of teleseismic waveforms recorded by 12 broad band stations of Iranian National Seismic Network (INSN) from 2004 to 2005 were used to study structure and thickness of the crust in different parts of Iran by joint inversion of receiver functions and regional surface wave group velocities. A combined inversion of body wave receiver functions and Rayleigh wave phase velocities increases the uniqueness of the solution over separate inversions and also facilitates explicit parameterization of layer thickness in the model space. However, receiver functions are mostly sensitive to sharp velocity contrasts, and relatively insensitive to the average velocity and to smooth velocity gradients. Group velocity dispersion is sensitive to average shear velocity over a broad range of depths between two seismic stations. While extremely useful for determining the general velocity profile with depth, dispersion techniques are largely insensitive to velocity discontinuities. Combining these complimentary tools in a single inversion allows for more unique analyses of crustal and upper mantle structure and increases the uniqueness of the solution over separate inversions and also facilitates explicit parameterization of layer thickness in the model space. Our results indicate an average crustal thickness which differs from 40 km beneach MAKU station in NW of Iran up to 56 km beneath NASN station. A Moho depth of 40 (+/-2) km beneath the MAKU station located in NW of Iran, consistent with gravity studies (Dehghani and Makris, 1984) and previous results (Tatar, 2001), indicates on existing of a thin crust in this part of Iran.

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