Crustal velocity structure and Moho discontinuity depth beneath center of Iran

Crustal velocity structure and Moho discontinuity depth have investigated beneath 7 the broadband seismic stations, AFRZ, TKDS, TPRV, TNSJ, ANAR, KRSH of the Iranian Seismological Center (ISC) and YZKH of Iranian National Seismic Network (INSN) located in the center of Iran by joint inversion of receiver functions and Rayleigh waves group velocity dispersion. Three years (2012 to 2014) teleseismic waveforms (with epicentral distance 25o-90o) for computation receiver functions by iterative approach in time domain have been processed. The Rayleigh waves group velocity dispersion curves were incorporated into our joint inversion scheme from an independent surface wave tomography study. Receiver function is response of local structure of ground (located beneath the three–component broadband seismic station) to teleseismic P-wave, that is sensitive to seismic discontinuities. Since there is very little absolute-velocity information contained in the receiver function, its inversion for shear-wave velocity structure is non-unique (velocity-depth trade-off). On the other hand, dispersion curves are sensitive to the average velocity structure of the upper layers rather than to seismic discontinuities. So the non-uniqueness problem can be solved by combining receiver function inversion with surface-wave dispersion. Results from joint inversion in center of Iran indicates that Moho discontinuity depth depth beneath AFRZ, TKDS and TPRV stations is 40 Km, beneath TKDS 42 Km, beneath ANAR is 38 Km and beneath KRSH and YZKH stations are 44 Km. It was shown that the joint inversion method can cause ±2 kilometers of error. The average Moho depth is about 42±2 kilometers beneath center of Iran.