S-WAVE ATTENUATION AND SPECTRAL DECAY PARAMETER FOR THE AVAJ REGION, IRAN*

Document Type: Regular Paper

Authors

1 Institute of Geophysics, Tehran University, Tehran, I. R. of Iran

2 2International Institute of Earthquake Engineering and Seismology, Farmanieh, Dibaji, 1953714453, Tehran, I. R. of Iran

3 International Institute of Earthquake Engineering and Seismology, Farmanieh, Dibaji, 1953714453, Tehran, I. R. of Iran

Abstract

The strong ground motions recorded during the 2002 Avaj earthquake have been used to estimate
S wave attenuation, Qβ, and spectral decay parameter, κ, for the Avaj region. Qβ for shear wave is estimated
as a function of frequency in the range of 0.6- 18 Hz. The results show that Qβ increases with frequency in the
form of Qβ=62.7 f 0.9. Our estimates are within the estimated range for different parts of the world for Qo and
n. The spectral decay parameter, κ, has been estimated from the high frequency of the spectra. The
dependence of κ on the epicenteral distance for the Avaj region is also found.

Keywords