Seismic hazard analysis using simulated ground-motion time histories: The case of the Sefidrud dam, Iran

This study aims at conducting probabilistic seismic hazard analysis for the Sefidrud dam located near Rudbar City. For this purpose, firstly, the characteristic earthquake recurrence model for major earthquakes on individual main faults have been combined with the smaller (smoothed) background seismicity of the region. Then, appropriate ground motion prediction equations were applied to estimate hazard values. Finally, in order to obtain reliable estimation of seismic hazard due to sources close to the dam site and to investigate near-field characteristics of motion, the Rudbar fault as the most prominent earthquake source in the immediate vicinity of the site is considered in seismic hazard computation using hybrid broadband simulation based ground motion parameters. The results of this method with different declustering schemes are reported for two level of seismic hazard analysis (i.e. return periods of 475 and 2475 years). Best estimate seismic hazard maps of PGA and PGV values obtained from the logic tree method is presented. By inclusion of simulation results for the Rudbar fault in the probabilistic seismic hazard analysis (PSHA), maximum PGA and PGV for 475 years return period obtained around 340cm/s/s and 25cm/s, respectively. For classic PSHA without including simulation the maximum PGA and PGV for 475 years return period obtained around 450cm/s/s and 32cm/s, respectively. With the simulation-based PSHA for a 2475 years return period a maximum PGA of 650cm/s/s and PGV of 50cm/s have been estimated. Classic PSHA (without simulation) for a 2475 years return period has resulted a maximum PGA of 850cm/s/s and PGV of 65cm/s. •Evaluation of simulated scenarios at most of stations confirms their good consistency with observed data.•Rise time, stress drop, and rupture velocity of selected scenario were modified slightly to obtain 27 scenarios.•As a result, PGA and PGV of Simulated ground motions from PSHA with simulation are less than PSHA without simulation.