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Regional electromagnetic induction around the Indian peninsula and Sri Lanka; a three-dimensional numerical model study using the thin sheet approximation

1989; Elsevier BV; Volume: 54; Issue: 3-4 Linguagem: Inglês

10.1016/0031-9201(89)90249-5

1872-7395

Ambuj Kumar Agarwal, J. T. Weaver,

Geological and Geophysical Studies

Abstract Further to other recent numerical studies of geomagnetic induction in southern India, the thin sheet algorithm developed at the University of Victoria has been used to investigate the three-dimensional problem of induction by a uniform source over the Indian peninsula and Sri Lanka. With this algorithm it is not necessary to assume that the region is surrounded by a normal structure, but the limitations imposed by grid size and the given conductivities for the crust and mantle have restricted our study to an inducing field of 20-min period. Solutions have been computed for two different models: (1) with only the conductivity contrast arising from land and seawater of variable depth present; and (2) with additional sub-surface conductors included in the Palk Strait/Gulf of Manowar region, underneath or near the Comorin Ridge and along the west coast fault. Results are presented for uniform magnetic sources oriented in both the northward and westward directions to distinguish the effect of different polarizations. The correspondence between the observed and computed Parkinson arrows at the southern array stations suggests the existence of the three sub-surface conductors.