Geophysical Observations on Christmas Island

Abstract

During October and November of 1961, the Marine Physical Laboratory of the Scripps Institution of Oceanography, in cooperation with the British Atomic Weapons Research Establishment, sponsored a series of geophysical measurements on Christmas Island. Continuous recordings of the earth's magnetic field were made simultaneously at various points on the island under the direction of Ronald G. Mason and John Northrop of the Marine Physical Laboratory of the University of California, San Diego. In addition to these recordings, daily trips by land rover and small boat to various points on the island and in the lagoon were made for the purpose of completing gravity and magnetic measurements with portable equipment. These measurements show a sharp positive gravity anomaly near Motu Tabu, towards the north end of the island, indicating a shallow depth to basement in that area