Geophysical Sub-Surface Characterization: Integrating Multi-Channel analysis of Surface Waves (MASW) Surveys for Enhanced Imaging and Interpretation-Paper

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The study applies Multichannel Analysis of Surface Waves (MASW) to characterize subsurface conditions at 12 sites in Bahraich district, Uttar Pradesh, a seismically active area near the Himalayan belt. MASW is a non-invasive method that estimates soil stiffness from shear-wave velocity (Vs), supporting seismic site classification and engineering decisions.<br /><br />Field surveys used a 24-channel seismograph with geophones spaced 2 m apart and a 15 kg sledgehammer as the seismic source. The recorded data were processed with ZondST2D software: Rayleigh-wave dispersion curves were extracted and inverted to produce one- and two-dimensional Vs profiles. Results were compared with borehole data and showed good agreement.<br /><br />Measured average Vs30 values ranged from approximately 186 to 291 m/s. Under the NEHRP 2020 classification, most sites were classified as Site D, while two were classified as Site DE. The profiles generally indicated relatively loose or soft soils in the upper layers, underlain by denser sand or stiffer clay. The authors note that these conditions may increase susceptibility to liquefaction during strong ground motion.<br /><br />The findings demonstrate that MASW can efficiently provide detailed subsurface information and complement conventional borehole testing. Such characterization can inform seismic hazard assessment, foundation design, and ground-improvement decisions for future construction in the region.

Keywords

MASW

shear-wave velocity

Vs30

seismic site classification

Bahraich district

Uttar Pradesh

Rayleigh-wave dispersion

subsurface characterization

liquefaction susceptibility

NEHRP 2020