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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />

(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />

Interior<br />

JSS008 Oral Presentation 1993<br />

Electromagnetic wave Anomaly of Earthquake and Signal Processing to<br />

Detect Precursor<br />

Prof. Masayasu Hata<br />

Computer Science Div. Chubu University <strong>IASPEI</strong><br />

Takashi Fujii, Ichi Takumi, Hirosi Yasukawa<br />

We have been studying an earthquake precursor of environmental electromagnetic waves (EM) at ELF<br />

band of 30-300Hz for the last twenty years. The observed signals contain local anomalous radiation of<br />

earthquakes as well as global background noise due to tropical thunderstorm. The global noise distorts<br />

the earthquake prediction. A method of global noise elimination is discussed by Independent<br />

Component Analysis (ICA). The second signal processing is to extract a precursor relevant to<br />

earthquake. For the processing, the linear predicting coefficient (LPC) method is applied. The LPC error<br />

was well acknowledged as a precursor of earthquakes exceeding magnitude five. In the paper, a new<br />

approach to extract precursor out of noisy ELF environmental signal by making use of Linear Predicting<br />

Coefficient, LPC signal model is introduced. For the case of Off-West-Fukuoka earthquake with M7.0, an<br />

anomalous magnetic flux radiation of about 10pT/√Hz with 1pT/√Hz background noise was detected<br />

about four days before the event at Tijiwa town Nagasaki Prefecture, 120km south of the epicenter, and<br />

five aftershocks exceeding M5.0 also followed respectively the anomalous radiations within one days<br />

delay. The radiation area was determined near the epicenter for both the main and aftershocks, by<br />

direction finding of the detected anomaly signal from two sites of Tijiwa and Tomochi through the signal<br />

amplitude ratio of EW to NS of sensing loop coils. These two facts may confirm the existence of EM<br />

precursor.<br />

Keywords: electromagneticwave anomaly, elf band, lpc

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