ATTENUATION LAW FOR THE STRONG MOTIONS IN IRAN

The attenuation of the Iranian strong motions is studied using the Iranian strong motions database. This database comprises ۴۶۸ three-components well recorded data (analog and digital) for which the teleseismic source parameters were available, or calculated from the strong motion records. The two-steps used attenuation model used in this study is log A=a.M-b.X-log X+c۱.S۱+σ.PWhere A is strong motion parameter, M is the moment magnitude, X is the hypocentral distance, and the coefficients a, h and c, are the coefficients of magnitude, distance and site effects (as ci, c۲, c۳, and ca for the four-class site classification) respectively. The sigma term represent the ۸۴ I% standard deviation with P=۱.