A Comprehensive Study on Seismic Site Characterization and Liquefaction Susceptibility Assessment (LSA) through Multi-channel Analysis of Surface Wave (MASW)

Multi-channel Analysis of Surface Waves (MASW) is a seismic exploration technique first introduced in geophysics by CB Park in 1999. It assesses sub-surface ground stiffness by measuring shear wave velocity (V _s ) in 1D, 2D, and 3D applied in diverse geotechnical engineering projects within the most common depth ranging from 0 to 30 meters. This non-intrusive seismic technique is widely used to draw out the V _s profile which illustrate the variation of soil velocity with depth. This paper details a novel approach to enhance the integration of MASW to seismic site characterization as per National Earthquake Hazard Reduction Programme (NEHRP) and Liquefaction Susceptibility Assessment (LSA) of seismically active 6 sites of Deoria district, Uttar Pradesh, these sites are situated very near to the seismically active Himalayan belt, which is vulnerable to great earthquake. Liquefaction poses a significant threat demanding accurate sub-surface characterization of seismically active sites. Seismically active sites seek to evaluate site-specific LSA by understanding local geologic, compositional, state, and historical criteria. MASW survey at all 6 locations was conducted by using a 24-channel PASI seismograph and 24 numbers of vertical geophones (natural frequency 4.5 Hz) situated at 2.0m intervals. A steel sledgehammer (15 kg) strikes on a steel plate to generate seismic waves. To develop and invert the surface wave seismic data to develop 2D depth versus V _s profiles, ZondST2D software was used. The average V _s30 of the current study area was found in between 158–370 m/s. Based on V _s30 seismic site characterization has been carried out. It was found that most of the sites fall in site class D. Some of the sites fall in site class DE as per NEHRP 2020 site classification. During Liquefaction Susceptibility Analysis (LSA), it was observed that most of the sites exhibited susceptibility to liquefaction up to a depth of 5.0 to 10.0 meters from the ground surface. The classification helped a preliminary understanding of the liquefaction susceptibility of sites chosen for the various geotechnical engineering projects.