On the Ultra-Low-Frequency Magnetic Field Depression for Three Huge Oceanic Earthquakes in Japan and in the Kurile Islands

Hayakawa, Masashi; Schekotov, A.; Fedorov, E. N.; Hobara, Y.

doi:10.5539/esr.v2n1p33

Cited by 9 publications

(6 citation statements)

References 14 publications

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“…Even with using the same ULF data, we can study a rather new topic of depression of ULF horizontal magnetic field initially discovered by Molchanov et al (2014) [75][76][77][78][79], which is the depletion in the intensity of nighttime irregular pulsations from the magnetosphere. This effect is not so popular even in the academic society, but it is suggested by them that this effect is attributed to the lower ionospheric turbulences [76,77] just like the subionospheric VLF/LF perturbation [16,30].…”

Section: Ulf Magnetic Field Depressionmentioning

confidence: 94%

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

et al. 2021

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The purpose of this paper is to discuss the lithosphere–atmosphere–ionosphere coupling (LAIC) effects with the use of multiparameter precursor observations for two successive Japanese earthquakes (EQs) (with a magnitude of around 7) in February and March 2021, respectively, considering a seemingly significant difference in seismological and geological hypocenter conditions for those EQs. The second March EQ is very similar to the famous 2011 Tohoku EQ in the sense that those EQs took place at the seabed of the subducting plate, while the first February EQ happened within the subducting plate, not at the seabed. Multiparameter observation is a powerful tool for the study of the LAIC process, and we studied the following observables over a 3-month period (January to March): (i) ULF data (lithospheric radiation and ULF depression phenomenon); (ii) ULF/ELF atmospheric electromagnetic radiation; (iii) atmospheric gravity wave (AGW) activity in the stratosphere, extracted from satellite temperature data; (iv) subionospheric VLF/LF propagation data; and (v) GPS TECs (total electron contents). In contrast to our initial expectation of different responses of anomalies to the two EQs, we found no such conspicuous differences of electromagnetic anomalies between the two EQs, but showed quite similar anomaly responses for the two EQs. It is definite that atmospheric ULF/ELF radiation and ULF depression as lower ionospheric perturbation are most likely signatures of precursors to both EQs, and most importantly, all electromagnetic anomalies are concentrated in the period of about 1 week–9 days before the EQ to the EQ day. There seems to exist a chain of LAIC process (cause-and-effect relationship) for the first EQ, while all of the observed anomalies seem to occur nearly synchronously in time for the send EQ. Even though we tried to discuss possible LAIC channels, we cannot come to any definite conclusion about which coupling channel is plausible for each EQ.

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Section: Ulf Magnetic Field Depressionmentioning

confidence: 94%

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

et al. 2021

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“…The spatial scale of ionospheric perturbations for the 2011 Japan Earthquake was considerably smaller, as compared with that for the 2004 Sumatra Earthquake. In addition, Hayakawa et al (2013) found a large depression of ULF (ultra-low-frequency) magnetic field variations observed on the Earth's surface on March 6. They also studied two other huge oceanic earthquakes in the Kurile Islands and found similar ULF depressions.…”

Section: M90 Tohoku-oki Earthquakementioning

confidence: 95%

Recent progress in ionospheric earthquake precursor study in China: A brief review

Liu

2015

Journal of Asian Earth Sciences

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“…Open Journal of Earthquake Research in Kyushu). The definition of this relative depression is given in [123] [124]. The top panel indicates the temporal evolutions of Dst and the occurrence of EQs with M greater than 5.…”

Section: Further Examplesmentioning

confidence: 99%

Seismogenic ULF/ELF Wave Phenomena: Recent Advances and Future Perspectives

Hayakawa¹,

Schekotov²,

Izutsu³

et al. 2023

OJER

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There has been enormous progress in the field of electromagnetic phenomena associated with earthquakes (EQs) and EQ prediction during the last three decades, and it is recently agreed that electromagnetic effects do appear prior to an EQ. A few phenomena are well recognized as being statistically correlated with EQs as promising candidates for short-term EQ predictors: the first is ionospheric perturbation not only in the lower ionosphere as seen by subionospheric VLF (very low frequency, 3 kHz < f < 30 kHz)/LF (low frequency, 30 kHz < f < 300 kHz) propagation but also in the upper F region as detected by ionosondes, TEC (total electron content) observations, satellite observations, etc, and the second is DC earth current known as SES (Seismic electric signal). In addition to the above two physical phenomena, this review highlights the following four physical wave phenomena in ULF (ultra low frequency, frequency < 3 Hz)/ELF

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On the Ultra-Low-Frequency Magnetic Field Depression for Three Huge Oceanic Earthquakes in Japan and in the Kurile Islands

Cited by 9 publications

References 14 publications

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

Recent progress in ionospheric earthquake precursor study in China: A brief review

Seismogenic ULF/ELF Wave Phenomena: Recent Advances and Future Perspectives

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