Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan

Uyeda, Seiya; Hayakawa, Masashi; Nagao, Tadami; Molchanov, O. A.; Hattori, Katsumi; Orihara, Yoshiaki; Gotoh, Kunihito; Akinaga, Y.; Tanaka, Haruo

doi:10.1073/pnas.072208499

Cited by 176 publications

(94 citation statements)

References 19 publications

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“…The above simultaneous appearance is strikingly similar with the one identified by Varotsos et al (2013) between the minimum b W,min of the fluctuations of the order parameter of seismicity and the pronounced SES activity observed by Uyeda et al (2002Uyeda et al ( , 2009 almost two months before the volcanic-seismic activity in 2000 in the Izu Island region, Japan.…”

Section: Discussionsupporting

confidence: 62%

“…This phenomenon has been reported by Varotsos et al (2013) who used as an example the pronounced SES activity with innumerable signals observed by Uyeda et al (2002Uyeda et al ( , 2009) almost two months before the onset of the volcanic-seismic swarm activity in 2000 in the Izu Island region, Japan. This swarm was then characterized by Japan Meteorological Agency (JMA) as being the largest earthquake swarm ever recorded (Japan Meteorological Agency 2000).…”

Section: An Ses Activity Initiates When the Fluctuations Of The Ordermentioning

confidence: 99%

“…Let us now investigate here whether this criterion is obeyed in the aforementioned case studied by Varotsos et al (2013). Along these lines, Varotsos et al (2014) Uyeda et al (2002Uyeda et al ( , 2009). In addition, Varotsos et al (2014) increased the magnitude threshold from M JMA = 3.4 to M JMA = 3.5 to assure a more safe data completeness.…”

Section: An Ses Activity Initiates When the Fluctuations Of The Ordermentioning

confidence: 99%

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M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

et al. 2017

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This paper reviews the precursory phenomena of the 2011 M W 9 Tohoku earthquake in Japan that emerge solely when we analyze the seismicity data in a new time domain termed natural time. If we do not consider this analysis, important precursory changes cannot be identified and hence are missed. Natural time analysis has the privilege that enables the introduction of an order parameter of seismicity. In this frame, we find that the fluctuations of this parameter exhibit an unprecedented characteristic change, i.e., an evident minimum, approximately two months before Tohoku earthquake, which strikingly is almost simultaneous with unique anomalous geomagnetic field variations recorded mainly on the z component. This is consistent with our finding that such a characteristic change in seismicity appears when a seismic electric signal (SES) activity of the VAN method (from the initials of Varotsos, Alexopoulos, Nomicos) initiates, and provides a direct confirmation of the physical interconnection between SES and seismicity.

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Section: Discussionsupporting

confidence: 62%

Section: An Ses Activity Initiates When the Fluctuations Of The Ordermentioning

confidence: 99%

Section: An Ses Activity Initiates When the Fluctuations Of The Ordermentioning

confidence: 99%

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M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

et al. 2017

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“…In particular, Varotsos et al (2013) found that these fluctuations minimize when a series of low-frequency (B0.1 Hz) electric signals (Uyeda et al 2002(Uyeda et al , 2009, termed Seismic Electric Signals (SES) activity, initiates (cf. these signals are generated when the gradually increasing stress in the preparation area of an impending earthquake reaches a critical value, e.g., see Varotsos et al 1993).…”

Section: Pðxþmentioning

confidence: 99%

Identifying the occurrence time of an impending major earthquake: a review

2017

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“…The selectivity and VAN relation are the backbone of the VAN method. In Japan, VAN-type telluric current monitoring was conducted and significant preseismic signals were observed in the late 1990s and early 2000s (6,8,9). The site in Kozu-shima Island was unique in showing SES-like telluric current changes before many EQs (9), whereas other stations showed such signals only for one EQ (6,8).…”

mentioning

confidence: 99%

Preseismic anomalous telluric current signals observed in Kozu-shima Island, Japan

Orihara

Kamogawa

Nagao

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Monitoring of telluric current, which is practically a synonym for geoelectric potential difference, was conducted on Kozu-shima Island about 170 km south of Tokyo from May 14, 1997 to June 25, 2000. During the monitoring period, 19 anomalous telluric current changes (ATCs) were observed. Their possible correlation with nearby earthquakes was statistically examined by assuming various lead times for different ranges of magnitude and focal distance. The best correlation may be obtained for earthquakes with a magnitude greater than 3.0 occurring within 20 km of focal distance. There were 23 such earthquakes, of which 11 were preceded by ATCs within 30 d. Of these 11 earthquakes, preceding ATCs of 5 and 6 were positive and negative polarities of telluric current, respectively. Their epicenters were spatially well clustered in the east and west of the island. These facts were clearly beyond those expected by chance and led to a simple speculative model.T he VAN method, named after the initials of Varotsos, Alexopoulos, and Nomicos, for short-term earthquake (EQ) prediction by means of the monitoring of preseismic telluric current signals, called seismic electric signals (SES), has been in successful practice since the 1980s (1). The VAN method, however, has been a contentious subject with regard to the causal relationship between SES and EQs (e.g., refs. 2, 3). One way to get around this would be to accumulate as many case studies as possible on one hand and to build plausible physical models on the other (1, 4, 5, 6).The VAN method is characterized by the notion of "selectivity," which has two aspects (3, 7): (i) there are only selected sites which are sensitive to SES, and (ii) a sensitive site is sensitive only to the SES from some specific focal area(s). A map identifying those focal area(s) is called the "selectivity map" of that site. The selectivity is thought to originate from inhomogeneity of the subterranean electrical structures, implying that SES is transmitted only through subterranean conductive channels (1, 4). Another remarkable property of SES, called the "VAN relation," is expressed by Eq. 1 in terms of the focal distance r, the magnitude M, and the amplitude E of SES.where a is a constant ∼0.34-0.37 and b is a site-dependent constant. The selectivity and VAN relation are the backbone of the VAN method. In Japan, VAN-type telluric current monitoring was conducted and significant preseismic signals were observed in the late 1990s and early 2000s (6,8,9). The site in Kozu-shima Island was unique in showing SES-like telluric current changes before many EQs (9), whereas other stations showed such signals only for one EQ (6,8). In addition, the EQs occurred in the east and west of Kozu-shima Island after the positive and negative polarities of the SES-like telluric current changes, respectively (9). So, in this paper we have tried to statistically examine the correlation between the SES-like telluric current changes and the EQs for Kozu-shima Island. In the following, the term "geoelectric potential dif...

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Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan

Cited by 176 publications

References 19 publications

M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

Identifying the occurrence time of an impending major earthquake: a review

Preseismic anomalous telluric current signals observed in Kozu-shima Island, Japan

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