Seismic site characterization and three-dimensional Vs modeling in Bukhara City, Uzbekistan

Abstract

This study presents an assessment of seismic site conditions in Bukhara City, Uzbekistan, based on ambient vibration measurements and HVSR (Horizontal-to-Vertical Spectral Ratio) analysis. Microtremor recordings were conducted at 45 measurement sites using a three-component digital seismometer. The acquired ambient vibration data were processed using the Nakamura method to determine the fundamental resonance characteristics of the subsurface soils. Subsequently, inversion of the HVSR curves was performed to estimate shear-wave velocity profiles and average shear-wave velocity in the upper 30 m (Vs30). Based on the obtained results, a spatial distribution map of Vs30 was developed for the study area. The analysis revealed significant spatial variability of soil seismic properties associated with the heterogeneous distribution of Quaternary sediments and ancient riverbed deposits. The obtained Vs30 values provide important information for seismic site classification and urban seismic hazard assessment. The results demonstrate the applicability of the microtremor HVSR method as a rapid and cost-effective tool for evaluating local site conditions in urban environments where conventional geophysical investigations are difficult to perform.