An Array Experiment with Magnetic Variometers Near the Coasts of South-east Australia

An array of magnetic variometers has been operated in the south-east corner of the Australian mainland, observing the coast effect simultaneously in two dimensions for the first time. The observations are presented as sets of variograms in the time domain and as contour maps of certain parameters in the frequency domain. Vertical field response functions are determined for each station, and the concept of fitting a surface over the area, using the response functions to define tangential planes, is introduced. By choosing different polarizations of the horizontal fields, the effects of the two coast lines, which are approximately at right angles to one another, can be distinguished. A major result is that for the East Coast, the enhanced vertical variations are not accompanied by significantly enhanced horizontal variations. The distinctive coast effect of the Bass Strait is noted, especially concerning the amplitude of the variations in the horizontal fields. There is a suggestion of an anomalous region in western Victoria, which may correlate with the ‘ Newer Volcanics ’ rock structure of the area. A quantitative interpretation is planned for a subsequent paper.