Seismogenic effects in ULF/ELF/VLF electromagnetic waves

Hayakawa, Masashi; Schekotov, A.; Izutsu, Jun; Nickolaenko, A. P.

doi:10.33665/ijear.2019.v06i02.001

Cited by 24 publications

(59 citation statements)

References 58 publications

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“…It is widely accepted that different kinds of electromagnetic (EM) phenomena which are possibly associated with lithospheric processes have been found prior to earthquakes (EQs), while their behavior and their possible interconnection have been investigated by the 2 of 26 scientific community for decades [1][2][3][4][5][6][7][8][9][10]. Moreover, it is also known that the ionosphere is sensitive to EQ preparation processes, and constitutes a very promising means of short-term EQ prediction [1].…”

Section: Introductionmentioning

confidence: 99%

Statistical and Criticality Analysis of the Lower Ionosphere Prior to the 30 October 2020 Samos (Greece) Earthquake (M6.9), Based on VLF Electromagnetic Propagation Data as Recorded by a New VLF/LF Receiver Installed in Athens (Greece)

Politis

Potirakis

Contoyiannis

et al. 2021

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In this work we present the statistical and criticality analysis of the very low frequency (VLF) sub-ionospheric propagation data recorded by a VLF/LF radio receiver which has recently been established at the University of West Attica in Athens (Greece). We investigate a very recent, strong (M6.9), and shallow earthquake (EQ) that occurred on 30 October 2020, very close to the northern coast of the island of Samos (Greece). We focus on the reception data from two VLF transmitters, located in Turkey and Israel, on the basis that the EQ’s epicenter was located within or very close to the 5th Fresnel zone, respectively, of the corresponding sub-ionospheric propagation path. Firstly, we employed in our study the conventional analyses known as the nighttime fluctuation method (NFM) and the terminator time method (TTM), aiming to reveal any statistical anomalies prior to the EQ’s occurrence. These analyses revealed statistical anomalies in the studied sub-ionospheric propagation paths within ~2 weeks and a few days before the EQ’s occurrence. Secondly, we performed criticality analysis using two well-established complex systems’ time series analysis methods—the natural time (NT) analysis method, and the method of critical fluctuations (MCF). The NT analysis method was applied to the VLF propagation quantities of the NFM, revealing criticality indications over a period of ~2 weeks prior to the Samos EQ, whereas MCF was applied to the raw receiver amplitude data, uncovering the time excerpts of the analyzed time series that present criticality which were closest before the Samos EQ. Interestingly, power-law indications were also found shortly after the EQ’s occurrence. However, it is shown that these do not correspond to criticality related to EQ preparation processes. Finally, it is noted that no other complex space-sourced or geophysical phenomenon that could disturb the lower ionosphere did occur during the studied time period or close after, corroborating the view that our results prior to the Samos EQ are likely related to this mainshock.

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Section: Introductionmentioning

confidence: 99%

Statistical and Criticality Analysis of the Lower Ionosphere Prior to the 30 October 2020 Samos (Greece) Earthquake (M6.9), Based on VLF Electromagnetic Propagation Data as Recorded by a New VLF/LF Receiver Installed in Athens (Greece)

Politis

Potirakis

Contoyiannis

et al. 2021

Entropy

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“…The middle panel in Figure 5 illustrates disturbances in the conductivity profile of the “TOP” type for the same magnitudes. In this model, the atmospheric conductivity deviates from the regular profile at altitudes exceeding 55 km (Hayakawa et al, 2008, 2019). We postulate that conductivity deviations at a height grow proportionally to the EQ magnitude 6 ≤ M ≤ 9.…”

Section: Possible Application Of Elf Records For Diagnostics Of Seismmentioning

confidence: 97%

“…The TOP model refers to modifications caused by atmospheric gravity waves bringing seismic energy to the upper part of the mesosphere, where the nonlinear phenomena take place modifying the air conductivity. The BOTTOM model may be attributed to changes in the air conductivity resulted from by the radon or other radioactive emanation from the EQ zone (Galuk et al, 2019; Hayakawa et al, 2019; Hayakawa & Molchanov, 2007; Pulinets & Ouzounov, 2011).…”

Section: Possible Application Of Elf Records For Diagnostics Of Seismmentioning

confidence: 99%

“…A lot of evidence has been accumulated during the last three decades indicating that the special electromagnetic phenomena take place prior to the EQs (e.g., see the books by Pulinets & Boyarchuk, 2004, Molchanov & Hayakawa, 2008, Surkov & Hayakawa, 2014, Hayakawa, 2015, Sorokin et al, 2015, and Ouzounov et al, 2018). There are two different categories in seismo‐electromagnetic phenomena: One is the direct emission from the lithosphere, and the other is the seismo‐atmospheric and seismo‐ionospheric perturbations (Hayakawa et al, 2019; Hayakawa & Hobara, 2010; Hayakawa & Molchanov, 2007; Uyeda et al, 2008). Among different kinds of seismogenic electromagnetic phenomena, especially, the ionosphere is already confirmed to be very sensitive to pre‐EQ seismic activity (e.g., Hayakawa et al, 1996, 2010; Liu, 2009; Molchanov & Hayakawa, 1998, 2008; Sorokin et al, 2015), which will be discussed later in this paper.…”

Section: Introductionmentioning

confidence: 99%

“…All the models of the varying EQ magnitude M EQ are characterized by the horizontal size ρ EQ of the area occupied by the disturbance. This size depends on the EQ magnitude M EQ in the following way (Dobrovolsky et al, 1979; Hayakawa et al, 2019; Ruhzin & Depueva, 1996):

ρ_{EQ} = \exp ((), M_{italicEQ}) .

…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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A significant anomaly in the extremely low frequency (ELF) spectra of Schumann resonance (SR) was discovered for the 1999 Chi‐Chi earthquake (EQ) in Taiwan as observed in Japan. Similar phenomena were confirmed for other EQs remote from the observer by a few megameters. An additional effect was detected for nearby EQs. The anomalies were explained by ELF radio wave scattering from a seismogenic disturbance. The global thunderstorms serve as the source positioned at the equator, and the localized seismogenic perturbation was placed above the EQ epicenter. We evaluate a seismic impact on SR power spectra using the realistic conductivity profile of atmosphere. The nonuniformity above EQ epicenter is axially symmetric varying along the radius according to Gaussian law whose scale depends on the magnitude. We use the complex characteristic heights relevant to the regular and disturbed cavities. These are substituted into the two‐dimensional telegraph equation (2DTE) for electric and magnetic fields. Deviations from the regular spectra are the seismogenic modifications that depend on the EQ magnitude. Computations indicate that a distant localized seismogenic nonuniformity provides a noticeable impact when the EQ magnitude exceeds the M = 7 threshold. The effect is also modeled of the nearby (up to 500 km) moderate (magnitude 5.5) EQs. The resonance spectra of disturbed fields become elevated as a whole. The distance dependence of field disturbance repeats seismogenic modifications in the characteristic heights above the observer. Model computations are compared with available observations.

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