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The observation of ULF emissions at Nakatsugawa in possible association with the 2004 Mid Niigata Prefecture earthquake


The observation of ULF/ELF electromagnetic emissions at Nakatsugawa, Gifu, has indicated that ULF emissions in the frequency below 0.1 Hz take place about two-three weeks before the 2004 Mid Niigata Prefecture earthquakes. The most important support to this is based on the goniometric direction finding for those ULF emissions in the period of October 2–6, which indicates their azimuth being very close to the epicenters of the earthquake. So, these ULF emissions on October 2–6 are likely to be associated with the 2004 Mid Niigata Prefecture earthquake.


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Correspondence to Masashi Hayakawa.

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Ohta, K., Watanabe, N. & Hayakawa, M. The observation of ULF emissions at Nakatsugawa in possible association with the 2004 Mid Niigata Prefecture earthquake. Earth Planet Sp 57, 1103–1108 (2005).

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Key words

  • Seismogenic ULF emissions
  • 2004 Mid Niigata Prefecture earthquake
  • goniometric direction finding