A magnetometer array study in northwest India

Abstract

A magnetometer array study has been carried out in northwest India, from Rajasthan across the Indo-Gangetic Plain into the Himalayan foothills. Over the three months of operation, a wide variety of natural geomagnetic events has been recorded. The analysis of a simple substorm, polarized just west of north, shows a strong anomaly in the form of a reversal of the vertical component of the fluctuation, both in the Himalayan foothills and on the Ganga Plain. The magnetic fluctuations pattern observed is most directly interpreted in terms of a path of concentrated current flow in the Earth, striking across the Himalaya. It is evidently aligned with the Aravalli belt which outcrops further south, and may indicate that some geological structure in the sub-basement is of abnormally high electrical conductivity. The path of such a current concentration across the foothills raises the question whether some transverse structure in the Himalaya is not acting as a bridge to Peninsular India for current induced in the Tibetan plateau to the northeast.