Estimation of Site Response and Qs Factor in the Khorasan Seismic Network Using Inversion Method

Site amplification in the Khorasan Seismic Network, Iran, was estimated using small earthquake events (ML ۱.۶-۵.۵) recorded from ۲۰۰۳ to ۲۰۰۶. This seismic network consists of ۵ broad band stations (NJ, MH, BJ, QU and SB) distributed in Razavi and North Khorasan provinces. A total of ۲۵۵ three-component waveforms from ۸۸ events were used in this study. The wide dynamic range of the Guralp instrument provided a broadband seismogram for S-waves. Site effects were estimated by linear inversion using the reference site (NJ). The S-wave quality factor was found to be approximated by the relation ۱۶۵f ۰.۴۸ in the frequency range ۰.۶-۱۰Hz. It was found that the siteamplification factor for three kinds of geometrical spreading model R-۱, R-۰.۷۵, R-۰.۵ was similar but the quality factor varied.