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Sarma, V. S.
- Multichannel Analysis of Surface Waves and High-Resolution Electrical Resistivity Tomography in Detection of Subsurface Features in Northwest Himalaya
Abstract Views :266 |
PDF Views:103
Authors
Affiliations
1 School of Earth and Environmental Sciences, Central University of Himachal, Dharamshala 176 207, IN
2 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
3 Ministry of Earth Sciences, Government of India, New Delhi 110 003, IN
1 School of Earth and Environmental Sciences, Central University of Himachal, Dharamshala 176 207, IN
2 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
3 Ministry of Earth Sciences, Government of India, New Delhi 110 003, IN
Source
Current Science, Vol 108, No 12 (2015), Pagination: 2230-2239Abstract
Geophysical studies using multichannel analysis of surface waves (MASW) and high-resolution electrical resistivity tomography (HERT) have been jointly carried out on an experimental basis in the field. The motive is to study shallow subsurface features (i.e. faults traces, cavities and palaeo-channels) in the foothill zone of Northwest Himalaya. These techniques have shown their potentiality in successfully identifying shallow (0-24 m) fault traces and dissolution features/palaeo-channels. Depending on the sensitivity of the MASW and HERT techniques, geophysical signatures of the subsurface features were recorded and further resolved with the help of synthetic simulation. The synthetic simulation of 2D electrical response has been carried out over the initial model for subsurface fault traces as well as palaeo-channels. The initial model has been refined iteratively to bring the synthetic response close to the field response and hence the final refined model is considered to be the true representation of the subsurface.Keywords
Fault Traces, High-Resolution Electrical Resistivity Tomography, Multichannel Analysis of Surface Waves, Synthetic Simulation, Palaeo-Seismology.- Dual Transmitter–Receiver Electromagnetic System for Lateral Boundary Detection of Subsurface Formations
Abstract Views :206 |
PDF Views:73
Authors
R. Rajesh
1,
V. S. Sarma
1
Affiliations
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
Source
Current Science, Vol 114, No 08 (2018), Pagination: 1747-1751Abstract
A new frequency domain electromagnetic system, based on different working principle has been designed and its efficacy tested over the existing systems through laboratory-scale-model studies. In this system, two transmitter coils have been employed to generate a magnetic null plane at their geometric centre. The receiver coil is placed in the null plane to record the induced secondary field. The interaction of the primary field is almost negligible on the secondary field recorded by the receiver. We present the theory and physical model results describing the system parameters and efficacy. The testing through physical model studies suggests an increased depth of detection in this new configuration compared to the existing systems. In terms of secondary field, the strength of the anomaly reflects the magnetic permeability/susceptibility difference of the subsurface medium on either side of the receiver. The study concludes that there is significant increase in depth of investigation and secondary field strength in this system over the existing conventional frequency domain systems and also more robust for boundary detection.Keywords
Conducting Bodies, Electromagnetic System, Magnetic Permeability, Physical Model Studies, Susceptibility.References
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- Resolution Enhancement for Geoelectrical Layer Interpretation of Electrical Resistivity Model from Composite Dataset:Implication from Physical Model Studies
Abstract Views :227 |
PDF Views:80
Authors
Affiliations
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
1 CSIR-National Geophysical Research Institute, Hyderabad 500 007, IN
Source
Current Science, Vol 116, No 8 (2019), Pagination: 1356-1362Abstract
Besides the high resolution offered by HERT, the resistivity models obtained using different electrode arrays differ significantly in geological structure and resistivity range. We combine the apparent resistivity data from multiple arrays to provide single resistivity model of high resolution as ‘composite method’. Initially, the method was tested on physical model data obtained over horizontal marble sheet kept in water. The parameters of target (resistivity, geometry, thickness) noticed in the resistivity model corresponding to composite method are appropriately matching with the true parameters. Finally, the method was applied to the data from Mahabubnagar, Telangana, India for groundwater studies. The resistivity model obtained using the proposed method has shown good match with regional hydro-geology and borehole data. The results from physical model as well as field data suggest plausible resolution enhancement in composite methodology for resolving thin layer(s) in 2D and 3D electrical resistivity tomography and induced polarization (IP) studies.Keywords
Electrical Resistivity Tomography, Groundwater, Induced Polarization, Physical Model Studies, Resolution Enhancement.References
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