Scattering of Extremely Low Frequency Electromagnetic Waves by a Localized Seismogenic Ionospheric Perturbation: Observation and Interpretation

Hayakawa, Masashi; Nickolaenko, A. P.; Galuk, Yu. P.; Kudintseva, I. G.

doi:10.1029/2020rs007130

Cited by 8 publications

(7 citation statements)

References 68 publications

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“…In contrast, occasional variations in SR intensity with extra-terrestrial origin have been associated only with solar proton events so far (Schlegel and Füllekrug, 1999;Roldugin et al, 2003), and recently, indication for periods with increased SR intensity during geomagnetic storms was demonstrated as well (Salinas et al, 2016;Pazos et al, 2019). We note that variations in SR were also reported connected to seismic activity (e.g., Christofilakis et al, 2019;Galuk et al, 2019;Florios et al, 2020;Hayakawa et al, 2020).…”

Section: Introductionmentioning

confidence: 52%

Solar Cycle-Modulated Deformation of the Earth–Ionosphere Cavity

et al. 2021

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The Earth–ionosphere cavity resonator is occupied primarily by the electromagnetic radiation of lightning below 100 Hz. The phenomenon is known as Schumann resonances (SR). SR intensity is an excellent indicator of lightning activity and its distribution on global scales. However, long-term measurements from high latitude SR stations revealed a pronounced in-phase solar cycle modulation of SR intensity seemingly contradicting optical observations of lightning from satellite, which do not show any significant solar cycle variation in the intensity and spatial distribution of lightning activity on the global scale. The solar cycle-modulated local deformation of the Earth–ionosphere cavity by the ionization of energetic electron precipitation (EEP) has been suggested as a possible phenomenon that may account for the observed long-term modulation of SR intensity. Precipitating electrons in the energy range of 1–300 keV can affect the Earth–ionosphere cavity resonator in the altitude range of about 70–110 km and modify the SR intensities. However, until now there was no direct evidence documented in the literature supporting this suggestion. In this paper we present long-term SR intensity records from eight stations, each equipped with a pair of induction coil magnetometers: five high latitude (|lat| > 60°), two mid-high latitude (50° < |lat| < 60°) and one low latitude (|lat| < 30°). These long-term, ground-based SR intensity records are compared on the annual and interannual timescales with the fluxes of precipitating 30–300 keV medium energy electrons provided by the POES NOAA-15 satellite and on the daily timescale with electron precipitation events identified using a SuperDARN radar in Antarctica. The long-term variation of the Earth–ionosphere waveguide’s effective height, as inferred from its cutoff frequency, is independently analyzed based on spectra recorded by the DEMETER satellite. It is shown that to account for all our observations one needs to consider both the effect of solar X-rays and EEP which modify the quality factor of the cavity and deform it dominantly over low- and high latitudes, respectively. Our results suggest that SR measurements should be considered as an alternative tool for collecting information about and thus monitoring changes in the ionization state of the lower ionosphere associated with EEP.

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Section: Introductionmentioning

confidence: 52%

Solar Cycle-Modulated Deformation of the Earth–Ionosphere Cavity

et al. 2021

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“…If we think of the EQ hypocenter as the zone where tectonic stress is accumulated, then we can expect different seismogenic perturbations in the atmosphere and ionosphere above the EQ epicenter. Even though Fidani [2006] suggested an alternative interpretation to our initial SR anomaly [Hayakawa et al, 2005], we assume that anomalous signals in the SR band may originate following our previous works [Hayakawa et al, 2005;Nickolaenko et al, 2006;Hayakawa et al, 2020a]. An EQ of magnitude M EQ reduces or increases the ionospheric height above the EQ zone.…”

Section: Model Of Seismogenic Modifications In the Lower Ionospherementioning

confidence: 52%

“…On the other hand, being closely related to the LAIC process, natural electromagnetic emissions are another important core of seismo-electromagnetics. Recently, Hayakawa et al [2019] have reviewed those naturally-occurring electromagnetic radiation in the frequency ranges of ULF (ultra low frequency), ELF (extremely low frequency) and VLF (very low frequency), and they have suggested the invaluable phenomena for short-term EQ prediction including ULF effects (lithospheric ULF radiation [e.g., Hayakawa et al, 2011], ULF depression as a signature of lower ionospheric perturbations [Schekotov et al, 2006[Schekotov et al, , 2013, atmospheric ULF/ELF electromagnetic emissions [Schekotov et al, 2007[Schekotov et al, , 2013[Schekotov et al, , 2017, and Schumann resonance (SR) anomalies [see a review by Hayakawa et al 2020a].…”

Section: Introductionmentioning

confidence: 99%

“…Those works are mainly concerned with the cases of distant EQs with a few Mm from the observing station. Recently, Hayakawa et al [2020a] addressed theoretically the expected SR anomalies from the nearby EQs. They have indicated the effect from nearby EQs as an enhancement of SR intensities arising from modulations of the local height gain coefficient.…”

Section: Introductionmentioning

confidence: 99%

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Schumann resonance anomalies associated with two (M~7) Tohoku offshore earthquakes in the spring of 2021

Hayakawa,

Izutsu,

Nickolaenko

et al. 2023

Annals of Geophysics

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ABSTRACT. We describe the Schumann resonance (SR) anomalies associated with two earthquakes (EQs) observed in Japan in the spring of 2021. SR is the global electromagnetic phenomenon observed in the ELF (extremely low frequency) band, and its resonance peaks are observed in the power spectra on natural radio noise at frequencies of 8, 14, 20, Hz, etc. The natural source of ELF radiation is the global lightning activity occurring in the Earth-ionosphere cavity. The anomalies were observed for the first time in Japan for the EQs in Taiwan when the distance between the observatory and the EQ epicenter was a few Mm (1 Mm = 1000 km). Recently, a new SR anomaly was addressed, related to nearby (a few hundred km) EQs (Hayakawa et al., 2019, 2020a,b). This paper presents the SR anomalies observed in the vicinity of Nagoya-city for two relatively close (~500 km) successive EQs with magnitude around 7 that occurred offshore the Tohoku area in Japan. The anomaly is characterized by the noticeable simultaneous increase or decrease in the amplitudes of three SR modes. This SR unusual behavior was observed prior to and after each of the two EQs that occurred in February and March, 2021. Observational data were interpreted in the model of seismogenic perturbations of the lower ionospheric conductivity profile. Model computations imply the full-wave solution of the ELF electromagnetic problem in the form of the Riccati equation and the 2D (two dimensional) telegraph equations. We show that observed disturbances in the SR power spectra might be attributed to two types of seismogenic modifications in the lower ionospheric profile: the compression or the expansion of the vertical profiles of mesospheric conductivity over the EQ epicenter.

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“…According to the observation, the magnitude of atmospheric vertical electric field before earthquakes almost reaches to the level of kV/m (Hao et al, 1998;Smirnov, 2008;Choudhury et al, 2013). The disturbed atmospheric conductivity before earthquakes was assumed as 10 −12 -10 −11 S/m near the ground in the model for Schumann resonance (Nickolaenko et al, 2006;Galuk et al, 2020;Hayakawa et al, 2020). From the calculation using the formula J = σ*E, the magnitude of disturbed electric current near the Earth's surface is 10 −9 -10 −8 A/m 2 .…”

Section: Location Of Disturbancesmentioning

confidence: 99%

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

et al. 2022

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Due to the complex processes of earthquake preparation, the observations and studies associated with earthquakes have attracted the attention of geophysicists for many years. The CSES was successfully launched on 2 February 2018. This satellite can provide global data of the electromagnetic field, plasma, and energetic particles in the ionosphere to monitor and study the ionospheric perturbations associated with earthquakes. Focusing on the characteristics of CSES, a spatial analysis method was proposed to extract the disturbances of electron density prior to earthquakes. Taking Indonesia Mw6.9 earthquake that occurred on 5 August 2018 as an example, the spatial method was illustrated and verified by another analysis method also using the data of electron density and GPS TEC data with the same analysis method. Based on the electron density of CSES for more than 2 years, this method was applied to carry out the statistical study prior to Mw ≥ 6.0 global earthquakes using the superposed epoch and space approach (SESA) method. It was found that 1) relative to the epicenters, seismo-ionospheric disturbances are more obvious in the equator direction than those in the polar direction; 2) the anomalies within 300 km distance from the epicenter are significant 11, 3, and 2 days prior to Mw ≥ 6.0 earthquakes; 3) the influence region of perturbances associated with earthquakes enlarges with the magnitude increase, and the stronger magnitude is the earlier disturbance appears. These statistical characteristics were not detected for the random earthquakes. Comparing the statistical result with the simulation output, the electric field pathway could be considered as the main channel of lithosphere–atmosphere–ionosphere coupling.

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Scattering of Extremely Low Frequency Electromagnetic Waves by a Localized Seismogenic Ionospheric Perturbation: Observation and Interpretation

Cited by 8 publications

References 68 publications

Solar Cycle-Modulated Deformation of the Earth–Ionosphere Cavity

Solar Cycle-Modulated Deformation of the Earth–Ionosphere Cavity

Schumann resonance anomalies associated with two (M~7) Tohoku offshore earthquakes in the spring of 2021

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

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