Geomagnetic variation anomalies in peninsular India

Abstract

Summary. Geomagnetic substorms recorded by an array of magnetometers over peninsular India have been analysed to investigate the subsurface electric configuration of the area. The study considered only night-time events when the external inducing field is uniform over the Indian peninsula and the conventional interpretational techniques of geomagnetic deep sounding can be readily applied. Contour maps of Fourier transform amplitudes and phases along with real and quadrature Parkinson arrows are presented. Their features reveal a complex anomaly pattern. The observed anomalies can be classified into: (i) southern peninsular anomalies, (ii) Palk Sirait anomalies, (iii) Pondicherry rift anomalies, and (iv) anomalies in the central region. A large-scale induction process seems to be disturbed by localized perturbations. The prominent anomaly observed over the southern tip seems to have a direct relevance to the tectonic setting of the Indian ocean and adjoining areas.