NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-4-513-2004 A direction finding technique for the ULF electromagnetic source Surkov V. V. 1 Molchanov O. A. 2 Hayakawa M. 3 Moscow Engineering Physics Institute, State University, Moscow, Russia Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia The University of Electro-Communications, Chofu Tokyo, Japan 20 09 2004 4 4 513 517 Copyright: © 2004 V. V. Surkov et al. 2004 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://nhess.copernicus.org/articles/4/513/2004/nhess-4-513-2004.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/4/513/2004/nhess-4-513-2004.pdf

A technique of direction finding is proposed, which can be applied to the magnetic-dipole type source located in the conductive ground. To distinguish a weak ULF source signal from the natural noise a network of multicomponent magnetometers is supposed to be used. The data obtained by the ground-based stations is processed in such a way that a set of partial derivatives of the magnetic perturbations due to the source are found. Comparing these derivatives with theoretical formulae makes it possible, in principle, to find the ULF source parameters such as the distance and amplitude. Averaging the data and a special procedure are proposed in order to exclude random fluctuations in the magnetic moment orientation and to avoid hydrogeological and other local factors.