Geomagnetic field fluctuations over Australia in relation to magnetic surveys

Abstract

Fluctuations of the earth's magnetic field with time can be a source of error of up to tens of nanotesla in magnetic surveying or prospecting. The best defence against possible difficulties such fluctuations may cause lies in understanding their origin, and their geographical uniformity or non-uniformity. The geographical uniformity of magnetic fluctuations has now been measured over several different areas of the Australian continent as part of research projects to examine natural electromagnetic induction taking place in the earth. The present paper shows examples of the results and gives some general description of magnetic fluctuations characteristics at coastlines, inland, and offshore. A major zone of non-uniform magnetic fluctuations has been detected in two places and may run north-south right across the continent.