Electrical structure of Garhwal Himalayan region, India, inferred from magnetotelluric

Abstract

Magnetotelluric investigations have been carried out in the Garhwal Himalayan corridor to delineate electrical structure of the crust along a profile extending from Indo-Gangetic Plane to Higher Himalayan region in Uttarakhand, India. The profile passing through major Himalayan thrusts: Himalayan Frontal Thrust (HFF), Main Boundary Thrust (MBT) and Main Central Thrust (MCT), and is nearly perpendicular to the regional geological strike. These Himalayan thrusts are broadly parallel to each other, steeper near surface and become shallow with the depth until they merge with the detachment surface. The main tectonic elements of Garhwal Himalayan region have an average strike of NW-SE (Khattri 1992). Magneto-variation (MV) studies (Arora et al 1982), were carried out over a rectangular array of 24 stations in the Siwalik Himalayan region, indicated the presence of a conductive anomaly, which they interpreted as an extension of the Aravallis and referred to as Trans Himalayan conductor. Subsequently, MT investigations were carried out by Gupta et al (1994) in the Siwalik region over 150 km long Mohand - Ramnagar profile to determine the thickness of Siwalik sediments. They recorded MT data in the frequency range 0.01–100 Hz using short period MT system and estimated geoelectric strike of N 800 W on the basis of