Determination of Causative Fault Parameters for the October 17, 2009, Ray-Tehran Earthquake, Using Near Field SH-Wave Data
H. Hamzehloo, F. Sinaeian, M. Mahood, H. Mirzaei Alavijeh, and E. Farzanegan
In this paper, the strong motion accelerograms of October 17, 2009, Tehran-Ray earthquake (MW=4.0) of south of Tehran were analyzed. (i) Using derived SH-wave spectral data, at first the parameters Ωo (long period spectral level), ∫c (corner frequency) and Q(f) (frequency dependent, average shear wave quality factor), appropriate for the best-fit Brune ω-۲ spectrum of this event were estimated. Then a non-linear least square analysis of the SH-wave spectral data was performed to provide objectively approximate near field estimates of the strike, dip and rake of the causative fault. Based on this analysis, the first fault plane solution has been presented for this event, which may be related to Eyvanaki fault closed to Tehran. Near field estimates of the strike, dip and rake of the causative fault of the 2009 Ray-Tehran earthquake are 292o, 36o, and 59o, respectively. Our estimated fault plane solutions suggest a reverse faulting mechanism with minor left lateral strike slip component. The estimated strike is consistent with the direction of isoacceleration map and Eyvanaki fault.