Crustal seismic anisotropy in the south-central Alborz region using Moho Ps converted phases

In this paper to find stable anisotropy direction with minimum error, we attempt to automate the choice of analysis of Moho Ps phase window by performing a grid search over different windows. We have determined the anisotropy direction in the crust of the Alborz region by using ۸ events recorded at three IIEES seismic broadband stations (i. e. DAMV, THKV and CHTH). Analysis of shear wave splitting of the Ps conversion from the crust-mantle boundary indicates a fast azimuth of anisotropy oriented approximately NE-SW. This strongly suggests coherent crustal anisotropy with a fast direction perpendicular to the strike of mountain block ranges. We estimate the average directions of anisotropy under three stations, DAMV, THKV and CHTH of ۴۲, ۵۵, ۵۵ degree, respectively. Moreover our results show that the magnitude of anisotropy are ۰.۲۳, ۰.۲۲, ۰.۲۷ seconds, respectively, which are in good agreement with the geology and tectonic setting of this region.

Keywords:

Anisotropy , Shear wave splitting , Ps converted phase , Grid searching , Anisotropy direction and magnitude , Receiver function