This study aims to estimate the dynamic effects of site conditions in Broujerd city through spectral analysis of microtremor data collected from 16 locations along two transects. By calculating the horizontal-to-vertical spectral ratio (H/V) and applying the HVTFA method, the natural period of alluvial deposits and amplification factors were determined. Additionally, Rayleigh wave ellipticity inversion was used to derive shear wave velocity profiles and seismic bedrock depth. Numerical modeling was carried out using DEEPSOIL (1D) and PLAXIS (2D) under linear conditions at low strain levels. The results revealed a significant correlation between experimental and numerical analyses, with natural frequencies ranging from 0.3 to 14.5 Hz. The maximum difference in natural period between H/V and 1D/2D models was 33%, indicating the influence of geometric and topographic effects in certain zones. Moreover, the seismic bedrock was found at depths corresponding to shear wave velocities greater than 750 m/s, consistent with national seismic codes. The study confirms that combined H/V and HVTFA methods, when integrated with numerical analysis, offer a reliable and cost-effective framework for seismic microzonation in complex urban environments.

Keywords: Microtremor waves, H/V method, HVTFA method, shear wave velocity profile, one-dimensional and two-dimensional dynamic analysis of alluvium, natural Period,.Seismic Site Model.