فهرست نشریات علمی دسترسی آزاد ایران

The decay parameter κ (Kappa) which was, first, presented by Anderson and Hough (1984) is commonly used to represent the observed decay of acceleration spectrum at high frequencies. It is considered that κ has a direct linear relationship with distance. The intercept of this line is called κ 0 , which is a site-dependent component, and it is supposed to be due to attenuation of seismic waves in near-surface layers. Nowadays, these decay parameters have various applications such as estimation of attenuation function in the square-root-impedance method or implementation of host to target method in ground motion prediction equations. However, the characteristics of both κ and κ 0 have not been studied, as it deserves. In the present paper, the decay parameter κ is obtained by the classical approach using 1157 records from all over Iran. The linearity of κ- distance relationship is questioned and investigated for different distances. It is found that the slope of κ- distance relationship reduces significantly at greater distances, and therefore, a linear correlation equation could not predict well enough specially for great distances. Furthermore, the log-likelihood (LLH) criterion is applied to select the best model that correlates κ 0 with V S 30 for different seismotectonic provinces of Iran. This criterion which is based on information theory yields that a linear equation can be a better correlation than a rational one. No asymptote value is observed for κ 0 at high values of V S 30 .