The Shallow <i>S</i>-Wave Structure in Beijing Plain Revealed by Surface Waves in Deep Seismic Reflection Survey: Insights into the Earthquake Risk Assessment

Abstract The occurrence of earthquakes and the resulting damage are closely related to both deep and shallow crustal structures. Although deep seismic reflection (DSR) surveys can effectively delineate the deep seismogenic structures, they are less capable of resolving the shallow structures above a few hundred meters. In this study, we derive a high-resolution shallow (0–300 m) VS model from surface waves in DSR data collected in the Beijing plain, using the frequency–Bessel transform method and a moving spatial window method. The VS model reveals that the shallow structures of the Beijing plain consist of alternating uplifts and depressions, corresponding to the Beijing Sag, Daxing High, Yangshuiwu buried hills, and Wuqing Sag. Comparisons with borehole data and shallow reflection surveys in Beijing Plain show that the VS model effectively resolves the fault displacement at depths of approximately 100 m, highlighting its potential for analyzing fault activity. We compare our VS model with the previously established VS model used in a ground motion simulation study, demonstrating that finer shallow subsurface structures are resolved by our VS model. In addition, we derive the VS30 values from our VS model. They are consistent with the VS30 values and the site classifications obtained from borehole data. Overall, this study demonstrates that the VS model derived from DSR data provides valuable insights into earthquake risk assessments.