Electromagnetic Induction and Telluric Currents in Northern New Zea1and

Abstract

The Bay of plenty is immediately north of the active volcanic region in the north island of New Zealand. The whole area is tectonically very active, being associated with oceanic crust descending beneath New zealand. To investigate the conductivity structure beneath the Bay of Plenty a joint study was organised between Prof. D.A. Christoffel of Victoria University of Wellington, and Dr Jean Filloux of Scripps Institution of Oceanography. Dr Filloux and his team from Scripps deployed an array of six seafloor magnetotelluric recorders which operated for three months, during which time the Victoria University team operated magnetotelluric recorders on land. This thesis presents the theoretical work and the data analysis performed to interpret the seafloor measurements. A major challenge of the analysis was to detect the effect of deep conductivity structures on the measured fields, in spite of the considerable distortion of the electric and magnetic fields associated with the coast.