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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 31, issue 9 | Copyright

Special issue: Dynamical processes in space plasmas II

Ann. Geophys., 31, 1597-1603, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 27 Sep 2013

Regular paper | 27 Sep 2013

Changes in the ultra-low frequency wave field during the precursor phase to the Sichuan earthquake: DEMETER observations

S. N. Walker1, V. Kadirkamanathan1, and O. A. Pokhotelov2 S. N. Walker et al.
  • 1ACSE, University of Sheffield, Sheffield, UK
  • 2Schmidt Institute of Physics of the Earth RAS, Moscow, Russia

Abstract. Electromagnetic phenomena observed in association with increases in seismic activity have been studied for several decades. These phenomena are generated during the precursory phases of an earthquake as well as during the main event. Their occurrence during the precursory phases may be used in short-term prediction of a large earthquake. In this paper, we examine ultra-low frequency (ULF) electric field data from the DEMETER satellite during the period leading up to the Sichuan earthquake. It is shown that there is an increase in ULF wave activity observed as DEMETER passes in the vicinity of the earthquake epicentre. This increase is most obvious at lower frequencies. Examination of the ULF spectra shows the possible occurrence of geomagnetic pearl pulsations, resulting from the passage of atmospheric gravity waves generated in the vicinity of the earthquake epicentre.

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