Articles | Volume 4, issue 4
Nat. Hazards Earth Syst. Sci., 4, 513–517, 2004

Special issue: Precursory phenomena, seismic hazard evaluation and seismo-tectonic...

Nat. Hazards Earth Syst. Sci., 4, 513–517, 2004

  20 Sep 2004

20 Sep 2004

A direction finding technique for the ULF electromagnetic source

V. V. Surkov1, O. A. Molchanov2, and M. Hayakawa3 V. V. Surkov et al.
  • 1Moscow Engineering Physics Institute, State University, Moscow, Russia
  • 2Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
  • 3The University of Electro-Communications, Chofu Tokyo, Japan

Abstract. 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.