Probing the lower ionospheric perturbations associated with earthquakes by means of subionospheric VLF/LF propagation

Hayakawa, Masashi

doi:10.1007/s11589-011-0823-1

Cited by 58 publications

(56 citation statements)

References 69 publications

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“…In addition, variations of some parameters in the ground, atmosphere and ionosphere during the preparatory phase of an earthquake can produce disturbances in the VLF/LF signals. As reported in many previous studies (Biagi et al, 2001a,b;Biagi and Hayakawa, 2002;Biagi et al, 2004Biagi et al, Q2 , 2005, 2008Hayakawa and Sato, 1994;Hayakawa et al, 1996Hayakawa et al, , 20062010;Morgounov et al, 1994; 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 Molchanov et al, 2006;Rozhnoi et al, 2004Rozhnoi et al, , 2005, 20072009), these disturbances are classified as anomalies; different analysis methods such as the residual dA/dP (Rozhnoi et al, 2004), terminator time TT (Hayakawa et al, 1996), Wavelet spectra and Principal-Component Analysis have been used (Biagi et al, , 2008. In this paper, we analyse some sampled LF signals in the framework of the European radio network, and using the Wavelet analysis, we investigate possible connections between anomalies in the radio signals and the M w ¼ 6.5 earthquake in Crete on October 12, 2013.…”

Section: Introductionsupporting

confidence: 69%

“…The first model assumes a direct effect because of gases (mainly radon), aerosol or electromagnetic emissions from the crust during the preparatory phase of an earthquake (Alperovitch, 1997;Biagi, 1999;Biagi et al, 2001b;Hayakawa and Sato, 1994;Pulinets et al, 1998). The second model assumes an indirect effect, which is the appearance of gravity waves in the atmosphere-ionosphere (Hayakawa et al, 1996;Molchanov and Hayakawa, 1998) that pre-seismic phenomena in the ground produce as an intensification of the microfracturing processes and/or changes in existing fissures in the rocks.…”

Section: Discussionmentioning

confidence: 99%

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The LF radio anomaly observed before the M w = 6.5 earthquake in Crete on October 12, 2013

Maggipinto

Biagi

Colella

et al. 2015

Physics and Chemistry of the Earth, Parts A/B/C

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a b s t r a c tOn October 12, 2013, an earthquake with M w ¼ 6.5 occurred in the southern Hellenic Arc, approximately 20 km off the west coast of Crete. The main shock, the focal depth of which is on the order of 40 km, was followed by aftershocks felt in the nearby cities and villages, although the aftershock sequence was poor. The epicentre was located at approximately 60 km from a radio receiver in Crete (CRE), which belongs to the European VLF/LF Radio Network. Several days before the earthquake, a clear disturbance occurred in one of the ten radio signals that the CRE receiver sampled. The disturbance, which can be considered an anomaly, appeared in the 216 kHz radio signal radiated by the Radio Monte Carlo (MCO) transmitter. The radio path MCO-CRE crossed directly over the epicentre area of the aforementioned earthquake. In this work, we present a detailed analysis of the MCO signal anomaly using spectral tools. We also investigate the behaviour of other radio signals sampled by the CRE receiver and consider other possible causes of disturbances on the MCO radio signal. We conclude that the disturbance in the MCO radio signal is a convincingly possible precursor of the earthquake in Crete. Emission of electromagnetic waves with a frequency band that includes 216 kHz from the focal zone of the earthquake can provide a satisfactory explanation of the radio anomaly.

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Section: Introductionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

The LF radio anomaly observed before the M w = 6.5 earthquake in Crete on October 12, 2013

Maggipinto

Biagi

Colella

et al. 2015

Physics and Chemistry of the Earth, Parts A/B/C

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“…The last, our own VLF/LF (very low frequency/ low frequency) network has been in operation for the last five years, and we currently have a network consisted of eight stations in Japan [22].…”

Section: Electromagnetic Phenomena In Possible Association With the Kmentioning

confidence: 99%

“…Here we will make full use of network observations of ULF magnetic field variations belonging to Japan Meteorological Agency (JMA), an ULF/ELF network by Chubu University [21], and our own VLF/LF subionospheric network [22].…”

mentioning

confidence: 99%

Electromagnetic Precursors to the 2016 Kumamoto Earthquakes

Schekotov¹,

Izutsu²,

Asano³

et al. 2017

OJER

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The Kumamoto area of Kyusyu Island was attacked by a series of large earthquakes (EQs) in April, 2016. The first two foreshocks had the magnitudes of 6.5 and 6.4, and about 1 day later there was the main shock on 15 April (UT) with magnitude 7.3. These are fault-type EQs, and so we would expect a variety of electromagnetic precursors to these EQs because we had detected different phenomena for the 1995 Kobe EQ, same fault-type EQ. As for the lithospheric effect, the ULF data at Kanoya observatory (about 150 km from the EQ epicenters) are used, but the simple statistical analysis could not provide us with any clear evidence of ULF radiation from the lithosphere. However, our conventional analyses indicated clear signatures in the atmosphere as ULF/ELF impulsive emissions and also in the ionosphere as observed by means of VLF propagation anomalies and ULF depression. ULF/ELF radiation appeared on 8-11 April (in UT) (maximum on 10 and 11 April (UT)), while ULF depression took place on 8 and 10 April (in UT), so that both atmospheric radiation and ionospheric perturbation took place nearly during the same time period.

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“…(e.g., Hayakawa 2012) and, probing by anomalous propagation of radio waves. The further reviews on the second category have been published regarding the atmospheric perturbations by Hayakawa (2009b) and on the ionospheric perturbations by Hayakawa (2009c), Liu (2009), andParrot (2009).…”

Section: Introductionmentioning

confidence: 99%

The Ionospheric Precursor to the 2011 March 11 Earthquake Based upon Observations Obtained from the Japan-Pacific Subionospheric VLF/LF Network

Hayakawa¹,

Hobara²,

Рожной³

et al. 2013

Terr. Atmos. Ocean. Sci.

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By using network observation of subionospheric VLF (very low frequency)/LF (low frequency) signals in Japan and in Russia, we have found a significant ionospheric perturbation prior to the recent 2011 March 11 Japan earthquake (EQ) which occurred at sea proximate to the Tohoku area on the main island (Honshu) of Japan was an exceptionally huge plate-type EQ. A remarkable anomaly (with a decrease in the nighttime amplitude and also with enhancement in dispersion) was detected on March 5 and 6 along the propagation path from the NLK (Seattle, USA) transmitter to Chofu (together with Kochi and Kasugai). We also have observed the corresponding VLF anomaly during a prolonged period of March 1 -6, with minima in the nighttime amplitude on March 3 and 4 along the path from JJI (Miyazaki, Kyushu) to Kamchatka, Russia. This ionospheric perturbation has been discussed extensively with respect to its reliability. (1) How abnormal is this VLF/LF propagation anomaly? (2) What was the temporal evolution of terminator times? (3) Were there any solar-terrestrial effects (especially the effect from geomagnetic storms) on the VLF/LF propagation anomaly? (4) The effect of any other EQs and foreshock activities on the VLF/LF anomaly? (5) Were there any correlations with other related phenomena? Finally, (6) are there any other examples of a VLF/LF propagation anomaly for oceanic EQs? We then compared the temporal properties of ionospheric perturbations for this EQ with those of a huge number of inland EQs and compared the corresponding spatial scale with the former result of the same oceanic 2004 Sumatra EQ with nearly the same magnitude. Finally, the generation mechanism of those seismo-ionospheric perturbations is briefly discussed.

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Probing the lower ionospheric perturbations associated with earthquakes by means of subionospheric VLF/LF propagation

Cited by 58 publications

References 69 publications

The LF radio anomaly observed before the M w = 6.5 earthquake in Crete on October 12, 2013

The LF radio anomaly observed before the M w = 6.5 earthquake in Crete on October 12, 2013

Electromagnetic Precursors to the 2016 Kumamoto Earthquakes

The Ionospheric Precursor to the 2011 March 11 Earthquake Based upon Observations Obtained from the Japan-Pacific Subionospheric VLF/LF Network

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