Estimation of kinematic source parameters and frequency independent shear wave quality factor around Bushehr

Abstract

In this paper, the shear wave quality factor and source parameters in the near field are estimated by analyzing the acceleration data in Zagros region. Accelerograms recorded by Building and Houses Research Center strong ground motion network have been used. The data have been considered with the magnitude of 4.7 to 6.3 collected from 1999 to 2014. In this approach, the theoretical S-wave displacement spectra conditioned by frequency independent Q was fitted with the observed displacement spectra. The source spectrum of an earthquake can be approximated by the omega-square ω² model, which has ω² decay for frequencies higher than the corner frequency. By following the mentioned approach, corner frequency, scalar moment, moment magnitude and frequency independent Q for each accelerogram were computed simultaneously, and the estimated error was given in the root-mean-square sense over the frequency range of interest. In this study, the generalized inversion method is used to estimate various source parameters as listed below. Thereby, it is estimated that the seismic moment range from 2.89E+23 to 1.21E+26 dyne-cm, average fault slip from 22 to 152 cm and average stress drop from 6 to 136 bars. The path average value Q are of the order Q=151-537.