Abstract
We present the concept of correction-factor model of rupture directivity and radiation pattern for empirical attenuation relations of peak ground velocity and acceleration response spectra. Approximate radiation pattern coefficients derived from accurate coefficients is used in this model. In addition, directivity function of bilateral line source by Boatwright (2007) based on directivity function of unilateral line source by Ben-Menahem (1961) is used in this model. The proposed correction-factor model for fault-normal and fault-parallel components has physically-based predictor variables and applicable to broadband distance from near-source to regional distance less than 200 km. We estimate regression coefficients of the model for strike-slip and dip-slip faultings using strong motion records of six crustal earthquakes with Mw>6.0 and verify the model by simulating the observed records.
