The observation of ultra‐low frequency emissions at Nakatsugawa, Japan, in possible association with the Sumatra, Indonesia, earthquake

Abstract

The observation of direct current (DC)/ultra‐low frequency (ULF) electromagnetic emissions at Nakatsugawa, Gifu, Japan, has indicated that ULF emissions in the frequency below 0.1 Hz took place about 3–10 days before the disastrous Sumatra, Indonesia, earthquake. The most important support to this is based on the goniometric direction finding for those ULF emissions during the period of 17–23 December, which indicates their azimuth angle being very close to the epicentre of the earthquake. So, these ULF emissions between 17–23 December are likely to be associated with the earthquake.

Acknowledgement

This work is partly supported by the Japan Society of Promotion of Science (#15403012), The Mitsubishi Foundation and ‘R and D promotion scheme funding international joint research’ by NiCT, to which we are grateful.