OasisLMS

A geophysical survey is a non-invasive tool for subsurface exploration, offering insights crucial for geological mapping, environmental assessment, and civil engineering projects. There are several geophysical surveys of soil exploration such as seismic refraction, electrical resistivity, magnetic method, and gravitational method, but Multi-Channel Analysis of Surface Waves (MASW) is one of the most versatile and advanced among them. MASW is a seismic exploration technique first introduced in geophysics by Park et al. (1999). It evaluates ground stiffness by measuring shear wave velocity (Vs) of sub-surface in 1D, 2D and 3D in various geotechnical engineering projects in the most common depth range of 0-30m. This non-obtrusive seismic method of MASW is prominently used to draw out the shear wave velocity profile (variation of velocity of soil 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) of seismically active 10 sites of Bahraich district, Uttar Pradesh, these sites are situated very near to the seismically active Himalayan belt, which is vulnerable to great earthquake. MASW survey at all 10 sites were conducted by using 24-channel PASI seismograph and 24 numbers of 4.5 Hz vertical geophones situated at 2.0m interval. Seismic power source was a (15 lbs) steel sledge hammer. To develop and invert the surface wave seismic data in addition to develop 2D depth versus shear wave velocity (Vs) profiles ZondST2D software was used. The average shear wave velocity of the current study area was found in between 214 -243 m/s. Based on shear wave velocity (Vs) seismic site characterization has been carried out and it was found that most of the sites fall in site D and some of the site fall in site DE as per NEHRP 2020 site classification. This research investigates the refinement and advancement of geophysical sub-surface characterization through the integration of Multi-Channel Analysis of Surface Waves (MASW) surveys.

Keywords: Geophysical survey; Muti-channel analysis of surface wave (MASW); Shear Wave Velocity (Vs); Sub-surface characterization; NEHRP

Neelu Patel, Motilal Nehru National Institute of Technology Allahabad, Prayagraj; MD Naseem Ahamad, Motilal Nehru National Institute of Technology Allahabad, Prayagraj; Vishwajeet Pratap Singh, Motilal Nehru National Institute of Technology Allahabad, Prayagraj

International Conference Proceedings