Global signal classification of ULF geomagnetic field variations using interstation transfer function

Harada, Makoto; Hattori, Katsumi; Isezaki, Nobuhiro

doi:10.1002/eej.20035

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…Recently, simultaneous use of wavelet transform and reference data (interstation transfer function) have been effective in getting around these difficulties (Harada et al 2003(Harada et al , 2004. A sensitive ULF geomagnetic network is now in operation over Kanto-Tokai area in Japan.…”

Section: Resultsmentioning

confidence: 99%

“…For this aim, the development of intense noise reduction method is important. Harada et al (2003Harada et al ( , 2004 propose the noise reduction method for global signals, which are originated from solar-terrestrial interaction, using the remote reference station. A mathematical model for geomagnetic fields is also possible for detecting anomalous geomagnetic field changes.…”

Section: Future Direction Of This Studymentioning

confidence: 99%

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ULF Geomagnetic Changes Associated with Large Earthquakes

Hattori¹

2004

Terr. Atmos. Ocean. Sci.

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3291 Marine Biosystems Research Center, Chiba University, Inage, Chiba, Japan *Corresponding author address: Prof. Katsumi Hattori, Marine Biosystems Research Center, Chiba University, Inage, Chiba, Japan; E-mail: hattori@earth.s.chiba-u.ac.jp Despite its extreme importance and years of effort, practical short-term earthquake prediction still remains to be seen. However, research in earthquake-related electromagnetic phenomena have recently shown that such phenomena make for a promising candidate for short-term earthquake prediction. There is a good deal of accumulated evidence of precursory signatures in a wide frequency range (DC-VHF). ULF geomagnetic change is one of the most promising phenomena and it suggests that short-term prediction is realizable. This report first reviews earlier observational facts and presents the latest results in detection of ULF emissions by means of sophisticated signal processing. Finally, we discuss the possible generation and propagation mechanism of earthquake-related ULF signals.

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Section: Resultsmentioning

confidence: 99%

Section: Future Direction Of This Studymentioning

confidence: 99%

ULF Geomagnetic Changes Associated with Large Earthquakes

Hattori¹

2004

Terr. Atmos. Ocean. Sci.

Self Cite

209

130

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“…However, it is essentially difficult to analyze the magnetic data by using a conventional FFT approach under the existence of the intensive transient noises due to man-made or global solar effects. Recently, simultaneous uses of WT and reference data have been effective in dealing with these difficulties (Harada et al, 2003(Harada et al, , 2004. Instead of FFT, we use WT in this paper.…”

Section: Data Analysis and Eqsmentioning

confidence: 99%

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

Febriani

Han

Yoshino

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Indonesia is one of the most seismically active regions in the world and mitigation of seismic hazard is important. It is reported that Ultra low frequency (ULF) geomagnetic anomalies are one of the most convincing phenomena preceding large earthquakes (EQs). In this paper we have analyzed geomagnetic data at Pelabuhan Ratu (PLR) (7.01 • S, 106.56 • E), Sukabumi, West Java, Indonesia, from 1 September 2008 to 31 October 2010. There are twelve moderate-large EQs (M ≥ 5) within 160 km from the station during the analyzed period. The largest one is the M = 7.5 EQ (depth = 57 km, epicentral distance = 135 km, 2 September 2009) based on EQ catalog of Indonesian Meteorological, Climatological and Geophysical Agency (BMKG). To investigate the ULF geomagnetic anomalous variations preceding all the EQs, spectral density ratio at the frequency range of 0.01 ± 0.003 Hz based on wavelet transform (WT) and detrended fluctuation analysis (DFA) have been carried out. The spectral density ratio results show the enhancements a few weeks before the largest EQ. The enhancement persists about one week and reaches a maximum on 16 August 2009. At the same time, the result of the DFA presents the decrease of α value. For other EQs, there are no clear increases of the spectral density ratio with simultaneous decrease of α value. When these phenomena occur, the value of Dst index shows that there are no peculiar global geomagnetic activities at the low latitude region. The above results are suggestive of the relation between the detected anomalies and the largest EQ.

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“…In this formula, where f indicates the frequency, the induction effects on the horizontal components are negligible (i.e., X s (f ) and Y s (f ) are the normal field variations). The contribution of anomalies to the vertical and horizontal geomagnetic field can be estimated by using the so-called interstation transfer functions (Schmucker, 1964;Beamish, 1982;Fujiwara and Tou, 1996;Vujić and Brkić, 2016;Harada et al, 2005). Let us assume the following:…”

Section: Data Analysis and Methodsmentioning

confidence: 99%

The geomagnetic coast effect at two 80° S stations in Antarctica, observed in the ULF range

et al. 2018

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Abstract. We examined the coast effect in Antarctica along the 80 • S magnetic parallel. We used the geomagnetic field measurements at the two coastal stations of Mario Zucchelli Station and Scott Base, and, as a reference, at the inland temporary station Talos Dome, during 18 January-14 March 2008. Spectral analysis in the Pc5 frequency range (1-7 mHz) revealed large differences between coastal and inland stations, such as higher spectral power levels in the vertical component and higher coherence between horizontal and vertical components at coastal stations. Using the interstation method on selected active time intervals, with Talos Dome as a remote reference station, we found that remote reference induction arrows are directed almost perpendicularly with respect to their respective coastlines. Moreover, the singlestation analysis shows that at Talos Dome the amplitude of the induction arrows is much smaller than at coastal stations. These results clearly indicate that coast effect at a few hundred kilometers from the coastline is relatively small. The coast effect on polarization parameters was examined, for a Pc5 event that occurred on 11 March 2008. The results evidenced that the azimuthal angle of polarized signals at one of the coastal stations is largely different with respect to the inland station (by ∼ 110 • ), while the polarization ratio and ellipticity attain comparable values. We proposed a correction method of the polarization parameters, which operates directly in the frequency domain, obtaining comparable azimuthal angles at coastal and inland stations.

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Global signal classification of ULF geomagnetic field variations using interstation transfer function

Cited by 7 publications

References 20 publications

ULF Geomagnetic Changes Associated with Large Earthquakes

ULF Geomagnetic Changes Associated with Large Earthquakes

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

The geomagnetic coast effect at two 80° S stations in Antarctica, observed in the ULF range

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