Magnetic measurements in the south-west Pacific Ocean

Abstract

Abstract Total magnetic force and bathymetric profiles totalling 25,000 km have been measured in the South-West Pacific Ocean between New Zealand, Fiji, and the Cook Islands. The magnetic anomalies exhibit characteristic patterns which may be correlated with different physiographic regions. Anomalies of amplitude less than 200 γ prevail over the Norfolk Basin, the flanks of the Tonga-Kermadec Ridge, and the South-West Pacific Basin north of 18° S, including the Manihiki Plateau. Amplitudes from 200 to 500 γ occur over the South Fiji Basin, Three Kings Rise, Colville Ridge, Havre Trough, and the South-West Pacific Basin south of 18° S; and with a marked short wavelength (<10 km) component over the North Fiji Basin, Hunter Ridge, and Lau Basin. The largest anomalies, with amplitudes between 500 and 1,000 γ, are found over the Kermadec Ridge. From a comparison of adjacent profiles there is an indication of a north-easterly trend in the magnetic anomalies over the Lan Basin between Fiji and Samoa. Model studi...