Site effect estimation in the Tehran basin and its impact on simulation results

Abstract

Recent earthquake damage distributions have demonstrated that the influence of local geology on ground shaking is a significant factor in engineering seismology. So, calculating the site effect is a priority to get a trustworthy assessment of the seismic risk for a location, in addition to studying the local seismic sources. The signal amplitude can be amplified by this effect throughout a range of periods. The site effect has been calculated using a variety of computational and experimental techniques, such as seismic noise measurements. In this study, to calculate the site effect, the analysis of accelerograms recorded by Iran’s strong motion network of the Road, Housing, and Urban Development Research Center was used. Here, 294 records from 63 stations were used to calculate the H/V (horizontal to vertical spectral ratio) curve as well as the near-surface high-frequency attenuation parameter (κ₀). The classification method is based on determining the peak period at each station. To examine site effect consideration, we use the hybrid method composed of the finite difference method for low frequencies (< 1 Hz) and a stochastic finite fault method for high-frequency radiation (> 1 Hz) to simulate an earthquake scenario on the Niavaran fault, which is located north of Tehran, Iran. According to the findings, different site classes cause spectral amplitude variations ranging from 11 to 28% at different periods (T = 0.2, 0.5, 1.0, and 4.0 s).