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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS013 Oral Presentation 2220
Crust and upper mantle anisotropy in the Central Alborz Region
Dr. Ahmad Sadidkhouy
Seismology Institute of Geophysics, Tehran University
Gholam Javan Doloei
During the last 3 decades, the determination of anisotropy is a subject of interest for seismologists. In
this study, we investigated anisotropy by shear wave splitting of Ps and SKS phases on broadband and
short period seismograms. When a shear wave propagates through an anisotropic medium, energy is
partitioned into orthogonally polarized fast and slow shear waves. This property is referred to as shear
wave splitting. In this study we used shear wave splitting of Moho Ps and SKS phases from teleseismic
to identify and estimate the shear wave anisotropy in the crust and upper mantle of the Alborz region
(IRAN). The use of Moho Ps phase to study anisotropy is potentially valuable since it is one of the few
ways to isolate the lower crust in the study of anisotropy. The SKS phase is a good tool for determining
of anisotropy because in an isotropic medium, there is no SKS energy on the transverse component so
that the presence of transverse energy indicates the rate of anisotropy. In this study, we selected
teleseismic events ( & for shear wave splitting of Ps method and for shear wave splitting of SKS
method) which were recorded in 3 broadband seismic stations, DAMV, CHTH and THKV (International
Institute of Earthquake Engineering and Seismology (IIEES)) and also 6 short period seismic stations,
FIR, DMV, AFJ, SHR, MHD and GZV (Institute of Geophysics, Tehran University, (IGTU)) for determining
anisotropy parameters in crust and upper mantle of the Alborz region. The majority of receiver functions
showed two different Ps phases before Moho Ps on radial component. We believed in that the first Ps
phase is generated in the upper crust (h