Seismic Microzonation of Shiraz City, Southwest of Iran

This paper aims to study the soil dynamics characteristics of central part of Shiraz city near the monument of Persepolis, southwest of Iran. The parameter investigated is natural period of soil sediment. The technique used to obtain this parameter is microtremor measurements. Microtremor measurements were obtained at 120 stations in the city. The data was recorded for two periods of fifteen minutes. Segmental Cross Spectra were applied to calculate spectra. Nakamura's method (H/V) was used for analyzing the measured data. At each site, natural period values were obtained. Because of low accuracy of amplification factors that achieved by microtremor measurements, this factor is neglected in this study. Iso-period map of this part of the city was prepared. The calculated natural periods were compared to those obtained through one dimensional analysis for some existing geotechnical borehole information. It showed that the predicted fundamental period by microtremor method compares well comparable to that obtained by one dimensional analysis.