An anomaly of ELF band vertical magnetic flux as a precursor of dome formation at Unzen volcano and its model analysis

Hata, Masaharu; Takumi, Ichi; Yabashi, Seiji; Tian, X

doi:10.1016/s0031-9201(97)90096-0

Cited by 7 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where (xi, yi, zi) is the coordinate of i-th observation site, c, the wave velocity, and ti the arrival time of the VLF of Earthquake-related Signals 35 signal at the i-th site. The equation is solved using the iterative method.…”

mentioning

confidence: 99%

Experiments to Locate Sources of Earthquake-related VLF Electromagnetic Signals.

Fujinawa

Takahashi

Matsumoto

et al. 1997

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

View full text Add to dashboard Cite

: Very low frequency (VLF) band electromagnetic signals')-") seem to be one of the most plausible precursory phenomena in the various kinds of anomalous electric, magnetic and electromagnetic field changes preceding earthquakes. In particular the number of VLF pulse-like signals has been known to increase clearly just before earthquakes2),4),9),10) possibly providing data on the occurrence time of impending earthquake. However, there is a lack of knowledge as to how to predict where the earthquake will strike. Also, it is difficult to establish the mechanisms of emissions induced by natural geophysical activity: earthquakes and volcanic eruptions. There are two main hypotheses regarding the generation mechanism of the VLF waves: the first proposes that electromagnetic waves are directly emitted from the hypocentral region,4),l0),'2>-15) while the second proposes that the emission is a result of electric charge redistribution in the Earth's atmosphere. 16)-is) Here, we present source region data for VLF pulse-like signals showing that the VLF emission does not originate around the epicenter but from regions of atmosphere above the epicenter spreading horizontally in several hundreds kilometers. Our data suggest that the VLF emission is produced by the electromagnetic processes in the Earth's atmosphere up to the ionosphere.

show abstract

mentioning

confidence: 99%

Experiments to Locate Sources of Earthquake-related VLF Electromagnetic Signals.

Fujinawa

Takahashi

Matsumoto

et al. 1997

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

View full text Add to dashboard Cite

show abstract

“…To study the electromagnetic induction and radiation which takes place during a swarm of earthquakes and volcanic eruptions, we have been conducting electromagnetic observations for a swarm of earthquakes that occurred in Itoh-city, Shizuoka, central Japan, in 1989(Hata, Yabashi, 1994. These were followed by eruptions in Unzen in Nagasaki prefecture on Kyushu Island, western Japan, which took place from 1991 to 1995 (Hata et al, 1998), and more recently, the eruption that occurred on Izu-Miyake Island, central Japan, in the summer of 2000.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, to reduce manmade noise, the observation frequency selected was the prime number of 223 Hz to the power line frequencies of 50 Hz and 60 Hz, with a narrow amplification bandwidth of less than 1 Hz. By making use of the highly sensitive electromagnetic wave receiver in the extremely low frequency band of 223 Hz, it was only possible to detect electromagnetic radiation in the cases of the Itoh-city earthquake swarm and the eruption in Unsen (Hata et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic-wave radiation due to diastrophism of magma dike growth in Izu-Miyake volcanic eruptions in Japan in 2000

Hata

Takumi

Yasuda

2001

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract.A large 10 cm per day diastrophism of the crust was experienced between Kozu and Niijima Islands during the Izu-Miyake volcanic eruptions in Japan on 3-4 August 2000. The diastrophism was detected through GPS observation. The seismometer also complied a swarm of earthquakes at this time. Our electromagnetic wave data, observed at 223 Hz at the Omaezaki site, about 110 km and 150 km northwest of the Kozu and Miyake Islands, respectively, detected a clear, anomalous magnetic flux radiation that corresponded well with the seismographic and GPS data. Similar radiation was received for about one week preceding the big volcanic eruption that occurred on 18 August 2000. These observations indicate that the electromagnetic wave monitoring system has the potential to monitor and/or warn of volcanic activity, and the facts disclose one of the mysterious radiation mechanisms of electromagnetic waves emitted from the Earth.

show abstract

Global Signal Elimination and Local Signals Enhancement from EM Radiation Waves Using Independent Component Analysis

Mouri¹,

Funase²,

Cichocki³

et al. 2008

IEICE Transactions on Fundamentals of Electronics, Communicatio

View full text Add to dashboard Cite

An anomaly of ELF band vertical magnetic flux as a precursor of dome formation at Unzen volcano and its model analysis

Cited by 7 publications

References 4 publications

Experiments to Locate Sources of Earthquake-related VLF Electromagnetic Signals.

Experiments to Locate Sources of Earthquake-related VLF Electromagnetic Signals.

Electromagnetic-wave radiation due to diastrophism of magma dike growth in Izu-Miyake volcanic eruptions in Japan in 2000

Global Signal Elimination and Local Signals Enhancement from EM Radiation Waves Using Independent Component Analysis

Contact Info

Product

Resources

About