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Sundararajan N.,Sultan Qaboos University | Seshunarayana T.,Council of Scientific and Industrial Research National Geophysical Research Institute
Arabian Journal of Geosciences | Year: 2013

Shear wave velocity (VS) estimation is of paramount importance in earthquake hazard assessment and other geotechnical/geo engineering studies. In our study, the shear wave velocity was estimated from ground roll using multichannel analysis of surface wave (MASW) technique making use of dispersive characteristics of Rayleigh type surface waves followed by imaging the shallow subsurface basaltic layers in an earthquake-prone region near Jabalpur, India. The reliability of MASW depends on the accurate determination of phase velocities for horizontally traveling fundamental mode Rayleigh waves. Inversion of data from surface waves resulted in a shear wave velocity (VS) in the range of 200-1,200 m/s covering the top soil to weathering and up to bedrock corresponding to a depth of 10-30 m. The P-wave velocity (VP) obtained from refraction seismic studies at these locations found to be comparable with VS at an assumed specific Poisson's ratio. A pair of selected set of VS profiles over basalt which did not result in a hazardous situation in an earthquake of moderate magnitude are presented here as a case study; in other words, the shear wave velocity range of more than 200 m/s indicate that the area is highly unlikely prone to liquefaction during a moderate or strong earthquake. The estimated depth to basalt is found to be 10-12 m in both the cases which is also supported by refraction studies. © 2013 Saudi Society for Geosciences. Source


Kumar D.,Council of Scientific and Industrial Research National Geophysical Research Institute | Mondal S.,Council of Scientific and Industrial Research National Geophysical Research Institute | Nandan M.J.,Council of Scientific and Industrial Research National Geophysical Research Institute | Harini P.,Council of Scientific and Industrial Research National Geophysical Research Institute | And 2 more authors.
Arabian Journal of Geosciences | Year: 2016

Groundwater investigation in a crystalline rock is a crucial task. A study was carried out at Choutuppal Telangana, India, under the pivotal research project of societal relevance. High-resolution electrical resistivity tomography (ERT) and time-domain-induced polarization (TDIP) dataset were collected in a granitic terrain to solve the groundwater problem as people are facing acute shortage of drinking water in the study area. The interpreted results derived from two-dimensional (2D) inverted resistivity models revealed substantial resistivity contrast between the weathered and massive granite and delineated three groundwater prospects zones, where the degree of weathering of fractured granite decreases with depth. On the other hand, the induced polarization (IP) results reflect marginal chargeability contrast, which indicates groundwater prospect zone. The basement of the hard rock aquifer system is clearly delineated showing very high resistivity with a range from 5000 to ~4 × 105 Ohm.m, which is confirmed by drilling at two places. Both the wells are drilled during the month of April and June, 2013, which are productive with a yield varying from 82.14 to 105 l/min. This study may help in future planning for groundwater exploration strategy and development for groundwater resources. © 2016, Saudi Society for Geosciences. Source

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