Reproducing fling-step and forward directivity at near source site using of multi-objective particle swarm optimization and multi taper

This paper presents a technique to reproduce compatible seismograms involving permanent displacement effects at sites close to the fault source. A multi-objective evolutionary algorithm is used to minimize the differences between the response spectra and multi-tapered power spectral densities corresponding to the recorded and simulated waveforms. The multi-taper method is used to reduce the spectral leakage that is inherent in the Fourier transformed form of waveforms, leading to a reduction of variance in power spectral amplitudes, thus permitting the calibration of the two sets of data. The technique is implemented using the 1998-Fandoqa (Iran) earthquake data and the results are compared with the actual observed data. Additionally, a comparison is made with a SAR interferometry study leading to fair agreement with the reported dislocation along the main fault. The simulation procedure and results are discussed and assessed concluding that, although the technique may be associated with uncertainties, it can still be used to reproduce waveforms at near source sites that include permanent dislocation, and can be used for seismic performance evaluation of structures in the region under study.