دانلود مقاله THE CRUSTAL STRUCTURE BENEATH THE IRANIAN PLATEAU FROM JOINT INVERSION OF RECEIVER FUNCTIONS AND SURFACE WAVES DISPERSION
سال انتشار: ۱۳۸۶
محل انتشار: پنجمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله
تعداد صفحات: ۷
Nasrabadi – International Institute of Earthquake Engineering and Seismology, Tehran, Iran
Tatar – International Institute of Earthquake Engineering and Seismology, Tehran, Iran
Priestley – Bullard Laboratories, Cambridge CB3 OEZ, UK
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. More than one year of teleseismic waveforms recorded by 11 broad band stations of Iranian National Seismic Network (INSN) 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. Information about the group velocity dispersion comes from tomographic images between 15 and 100 s period produced by a study of regional fundamental mode Rayleigh waves propagating across Iran and surrounding regions (Rham et al., 2006). The preliminary results indicate an average crustal thickness which differs from 35 km beneach MAKU station in NW of Iran up to 55 km beneath most of the INSN stations. AMoho depth of 35 (+/-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.