Multichannel Analysis of Surface Waves and High-Resolution Electrical Resistivity Tomography in Detection of Subsurface Features in Northwest Himalaya

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.