Subsurface Characterisation using Multichannel Analysis of Surface Waves (MASW) at SGSITS, Indore

Abstract

Geophysical investigations are conducted at the start of the site research process to characterize the subsurface and classify the seismic site. The reflected wave from the seismic source is recorded by a series of receivers called "Geophones" that are coupled to a processing system in such seismic studies. MASW (Multichannel Analysis of Surface Waves) is one such exploration approach that uses the Shear Wave Velocity (Vs) of the subsurface to derive numerous geotechnical and geophysical data. 2 MASW surveys are conducted at SGSITS campus, and various subsurface parameters such as SPT-N value, Poisson ratio, Young's Modulus, Shear, and Bulk Modulus are determined for each location. The locations are also characterised in preparation for Seismic Site Design. The recorded MASW data is analysed with the winMASW software, and the location is classified using the NEHRP (National Earthquake Hazard Reduction Program) and average shear wave velocity for 30m (Vs30). The values of Vs30 for 2 sites are 435m/s and 375m/s. These meet the definition of "Site Class C" based on data analysis for numerous locations. Therefore, SGSITS, Indore can be categorized to fall under the “Site Class C” as per NEHRP Classification.