<p>In the geotechnical field, sediment layer thickness determination is critically important, as it provides invaluable information for structural and infrastructure planning and design. The Bakauheni area, characterized by numerous calderas and ancient volcanic deposits from the Pliocene to Holocene epochs, presents a compelling case for studying sediment layer thickness. Using 64 Horizontal-to-Vertical Spectral Ratio (HVSR) measurement points, we investigated sediment thickness distribution and its correlation with ancient calderas in Bakauheni. A 1D shear wave velocity (<i>Vs</i>) model was derived through inversion using the Particle Swarm Optimization (PSO) algorithm, revealing an average <i>Vs</i> of ~ 600 m/s across the study area. This relatively high <i>Vs</i> value suggests dense, compacted sediments or weathered bedrock. The average HVSR curve yielded a natural frequency (<i>f</i>₀) of 15.12 Hz, corresponding to an estimated sediment thickness of 9.92 m (assuming <i>Vs</i> = 600 m/s). This aligns closely with the median thickness of 10.55 m calculated from all 64 measurement points. Observed sediment thicknesses ranged from 4.39 to 103.57 m, with a mean of 18.22 m, indicating a general thickness range of 10–18 m in Bakauheni. The thickest deposits (&gt; 30 m) correlate with caldera locations and low-topography zones, implying substantial sediment accumulation over ancient calderas. While the HVSR method effectively estimates sediment thickness for caldera identification, local <i>Vs</i> variations due to sediment composition necessitate further research to fully characterize the subsurface properties.</p>