On the statistical correlation of over-horizon VHF signals with meteorological radio ducting and seismicity

Yonaiguchi, N.; Ida, Y.; Hayakawa, Masashi

doi:10.1016/j.jastp.2007.01.007

Cited by 28 publications

(11 citation statements)

References 13 publications

(22 reference statements)

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“…Pre-seismic emissions: Rock motions stimulate emissions that ultimately affect the total electron density in the ionosphere Atmospheric electric field variations Kondo (1968), Kamogawa et al (2004) Changing infra-red emissions from surface, suggesting release of gas Surkov et al (2006) Over-the-horizon VHF emissions, suggesting changed properties of air Hayakawa (2006), Yonaiguchi et al (2007) Total The local current flowing depends on the local columnar resistance R c , which has significant contributions from the lowest atmosphere and the free troposphere (FT), and a small ( $ 7%) contribution from the stratosphere. Changes in the resistance of the atmospheric boundary layer (BL), through the release of radioactive gases into the surface layer, modify the total columnar resistance, and hence modify the conduction current flowing.…”

Section: Mechanism Supporting Observation Example Referencesmentioning

confidence: 99%

Atmospheric electricity coupling between earthquake regions and the ionosphere

Harrison

Aplin

Rycroft

2010

Journal of Atmospheric and Solar-Terrestrial Physics

159

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a b s t r a c tWe propose a mechanism to explain suggested links between seismic activity and ionospheric changes detected overhead. Specifically, we explain changes in the natural extremely low-frequency (ELF) radio noise recently observed in the topside ionosphere aboard the DEMETER satellite at night, before major earthquakes. Our mechanism utilises increased electrical conductivity of surface layer air before a major earthquake, which reduces the surface-ionosphere electrical resistance. This increases the vertical fair weather current, and (to maintain continuity of electron flow) lowers the ionosphere. Magnitudes of crucial parameters are estimated and found to be consistent with observations. Natural variability in ionospheric and atmospheric electrical properties is evaluated, and may be overcome using a hybrid detection approach. Suggested experiments to investigate the mechanism involve measuring the cut-off frequency of ELF ''tweeks'', the amplitude and phase of very low frequency radio waves in the Earth-ionosphere waveguide, or medium frequency radar, incoherent scatter or rocket studies of the lower ionospheric electron density.

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Section: Mechanism Supporting Observation Example Referencesmentioning

confidence: 99%

Atmospheric electricity coupling between earthquake regions and the ionosphere

Harrison

Aplin

Rycroft

2010

Journal of Atmospheric and Solar-Terrestrial Physics

159

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“…To find out the relation between the anomalous propagation and seismicity, we adopted statistical analysis to the observational results and calculated the probability gain, which is the ratio of the observational probability to the non-related probability. These are further distinguished from the previous reports (Fujiwara et al, 2004;Yonaiguchi et al, 2007).…”

Section: Introductionmentioning

confidence: 56%

“…Other researchers inferred that the anomalous propagation was influenced by the perturbation in the troposphere. They considered that the perturbed region was within a radius of 100 km from the epicenters of earthquakes (Yonaiguchi et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Stochastic relation between anomalous propagation in the line-of-sight VHF radio band and occurrences of earthquakes

Motojima

Haga

2014

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper was intended to find out any relation between anomalous line-of-sight propagation on the very high frequency (VHF) band and occurrences of earthquakes near the VHF propagation paths. The television and FM radio broadcasting waves on the VHF band were monitored continuously over the long term. For that purpose, a multidirectional VHF band monitoring system was established and utilized. Anomalous line-of-sight propagation on the VHF band was distinguished from the monitored wave by using a statistical analysis. After the stochastic consideration, it was found out that earthquakes associated with anomalous propagation were characterized by magnitude of earthquakes M ≥ 4.5, and distances from epicenters L ≤ 75 km. The anomalous propagation was monitored on the VHF band a few days before the associated earthquakes occurred. Moreover, the anomaly appeared on multidirectional propagation paths simultaneously. The anomaly on the line-of-sight propagation indicates the possibility of narrowly focusing the area of the epicenter of earthquake.

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“…An anomaly in ionosphere appears a few weeks prior to earthquake associated with it (Muto 20 et al, 2009;Chakrabarti et al, 2010). Especially, some anomalies in signal amplitude and phase around sunrise and sunset times appeared a few days prior to the Kobe Japan earthquake, which occurred on 17th January 1995 (Molchanov and Hayakawa, The other hand, there are many papers which report anomalous propagation in the VHF band waves from over-horizon broadcasting stations (Yonaiguchi et al, 2007). Yasuda et al (Yasuda et al, 2009) reported that the anomalous propagation associated with earthquake occurs in the troposphere, and the anomaly affects the propagation path more 100km or so away.…”

Section: Introductionmentioning

confidence: 99%

Stochastic consideration of relationship between occurrences of earthquake and fluctuations in the radio wave propagation

Motojima

Tanigawa

Haga

2017

Preprint

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Abstract. Research of the geophysical electromagnetic phenomena with seismic activity is important for hazard-resistant strategy. Many papers which indicate the existence of geophysical electromagnetic phenomena associated with earthquakes are reported frequently. Anomalous propagation in the radio waves is sometimes related with earthquakes. In previous paper, authors proposed a new concept to estimate the relation between earthquakes and anomalous line-of-sight propagation in VHF band by statistical approach. Event probability of the anomalous line-of-sight propagation increased just a few days prior 5 to earthquakes. In this paper, we investigated a new relationship between anomalous fluctuations in the radio waves, which propagated from line-of-sight region, and occurrences of earthquake by using statistical analysis. Monitoring the strength of radio waves and detecting the anomalous fluctuations by using a new original method, we can obtain the high probability which indicates strong relation between the anomalous propagation and occurrences of earthquake. After the stochastic consideration, we can find out the anomalous fluctuations, which appear one day prior to earthquakes near the wave propagation path.

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On the statistical correlation of over-horizon VHF signals with meteorological radio ducting and seismicity

Cited by 28 publications

References 13 publications

Atmospheric electricity coupling between earthquake regions and the ionosphere

Atmospheric electricity coupling between earthquake regions and the ionosphere

Stochastic relation between anomalous propagation in the line-of-sight VHF radio band and occurrences of earthquakes

Stochastic consideration of relationship between occurrences of earthquake and fluctuations in the radio wave propagation

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