Spectral Attenuation Characteristics of Strong Ground Motions in East-Central Iran Using Theoretical Data

Ground-motion prediction equations are an essential element of PSHA. In seismic hazard analysis, attenuation calculations determine how quickly ground motions decrease as the distance from a seismic event increases. The estimation of ground motion for future earthquakes as a function of magnitude and distance is an important problem from earthquake engineering point of view. This article presents spectral equations for the estimation of horizontal strong ground motions caused by shallow crustal earthquakes with magnitude range of Mw 5.0 to 7.4 and distance to the surface projection of the fault less than 100 km for theoretical (simulated) records. The reason for development of ground motion in this region is that strong ground motion data are too sparse to allow ground motion relations to be derived directly from sufficient observed data. By considering the modeling parameters, we have used the stochastic finite fault modeling to generate a large suite of acceleration time histories for this region. The attenuation characteristics of horizontal spectral accelerations of strong motion in near-field are studied in this paper and the attenuation relations for horizontal acceleration response spectrum in the period range of 0.1–5 s for rock classification in the East-Central Iran are established. These equations were derived by two-stage regression analysis, on a set of 1200 theoretical strong-motion records generated in this area. The present results will be useful in estimating strong ground motion parameters and in the earthquake resistant design in the East-Central Iran region