Studying Site Effect in Shahreza City by Using Microtremor Measurement & Vulnerability Index

Regarding to the destructive earthquakes that happened in the world and Iran, potential influence of surface geology on strong ground motion and the damages due to the earthquakes that named as site effect is well known. This study is a section of seismic microzonation of Shahreza city. In this study we further investigated the site effect by microtremor measurement and for analysis of microtremor data; H/V (Nakamura's technique) was used. Accordingly, the microtremor measurement has been estimated for 64 sites of Shahreza city. Finally, the results are presented in different maps as natural period distribution of site, amplification factors and Vulnerability Index. The calculations revealed that the natural period is differing from 0.04 to 0.38 and the amplification factor differs from 1.21 to 6.88, too. The results showed a relatively acceptable connection with the morphology of the region. Thus, the natural period is decreased by moving toward the mountains around the city, whereas the natural period is increased by moving toward the center of plain. The results of this study as preliminary investigation can be used with detailed investigations in metropolitan planning for Expansion of City, estimation of seismic risks and crisis management due to an earthquake.