Variation of Altitude Observed on the Occasion of the Tohoku Earthquake (M = 9.0) Occurred on March 11, 2011

Milillo, Pietro; Maggipinto, T.; Biagi, P. F.

doi:10.4236/ojer.2014.31004

Cited by 3 publications

(4 citation statements)

References 7 publications

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“… Chen et al [2011] have found from the analysis for many EQs in Taiwan that significant surface changes are observed several days before an EQ (when we have a lot of seismo‐electromagnetic phenomena). The similar analyses by using the GPS data have been carried [ Milillo et al , 2012; K. Hattori, private communication, 2012], which have reported similar pre‐EQ surface variations. Of course, we need much more evidences on these surface variations, but we can say, at the moment, that a physical process has been identified to be really existing, producing the atmospheric oscillations (or AGW and/or AW).…”

Section: Conclusion and Discussionsupporting

confidence: 60%

The observation of Doppler shifts of subionospheric LF signal in possible association with earthquakes

et al. 2012

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The Doppler‐shift observation of LF (f = 60 kHz) subionospheric signal from Saga (Kyushu) (with call sign of JJY) as observed at Chofu (CHF), has been used to investigate the properties of ionospheric perturbations possibly associated with earthquakes(EQs). The period of analysis is seismo‐active half a year from January 1, 2009 to June 30, 2009, and six EQs with magnitude greater than 5.0 (in a range from 5.1 to 5.8, which took place within the wave sensitive area of the JJY‐CHF path) are dealt with. It is found from the Doppler‐shift observation at CHF that the Doppler shifts are really observed and the components in the frequency ranges of AGW (atmospheric gravity wave) and AW (acoustic wave) in the Doppler shifts are clearly enhanced, at least, before each EQ. This observational fact would lend a strong support to the important role of atmospheric oscillation channel in the lithosphere‐atmosphere‐ionosphere coupling mechanism.

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Section: Conclusion and Discussionsupporting

confidence: 60%

The observation of Doppler shifts of subionospheric LF signal in possible association with earthquakes

et al. 2012

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“…Recently some researchers have tried to find some ground motions before an EQ on the basis of analyses of available GPS data, who have found that the ground motion is recognized several days before EQs (Chen et al, 2011;Milillo et al, 2012;Hattori, private communication, 2012). The presence of such a kind of ground motions would be a definite answer to our ad-hoc assumption of the AGW hypothesis.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Further, some "direct" evidence of this channel was recently provided by Asai et al (2011) on the basis of Doppler-shift observations of the real AGW in the seismo-ionospheric intercation, because the Doppler measurement provides the direct information about the ionosphere, unlike our previous study of AGW fluctuation in the sub-ionospheric VLF data. Important additional information is that some evidence has recently supported the ad-hoc assumption of the AGW concept: significant surface changes were observed several days before an EQ (Chen et al, 2011;Milillo et al, 2012;Hattori, private communication, 2012).…”

Section: Introductionmentioning

confidence: 99%

An evidence on the lithosphere-ionosphere coupling in terms of atmospheric gravity waves on the basis of a combined analysis of surface pressure, ionospheric perturbations and ground-based ULF variations

Nakamura

Korepanov

Kasahara

et al. 2013

JAE

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One major candidate of lithosphere-atmosphere-ionosphere (LAI) coupling mechanism is through atmospheric oscillations triggered near Earth's surface due to some pre-earthquake (EQ) effect, and this channel has been extensively proved by using meteorological disturbances much more easily treated than pre-EQ effects (Korepanov et al., 2009). In the present paper this channel is challengingly studied, for the first time, for pre-EQ phenomena, and we take a rather strong EQ named Niigata-chuetsu EQ on 23 October, 2004 (with magnitude of 6.8 and with depth of 13 km) for which we already know that the ionospheric perturbation did take place prior to the EQ . In this paper the LAI coupling has been intensively studied by means of coordinated observational data (surface atmospheric pressure data as an indicator of atmospheric gravity waves (AGWs), our own subionospheric VLF/LF data as a measure of ionospheric perturbations and the ground-based ULF data as a measure to monitor the modulation in the ionospheric dynamic region). The wavelet analyses for these parameters in different spatial regions have all indicated the enhancements of fluctuations in the wave frequency of 10 ~ 100 min (in the frequency range of AGWs). The correlation of wavelet spectra between the atmospheric pressure and VLF/LF amplitude has yielded a high value with the delay of a few hours, while there is nearly no distinct delay of the wavelet spectra between the ionospheric perturbation and the ground-based ULF fluctuation. These observational facts are compared with the theoretical estimation of AGW hypothesis, which may provide a convincing support to the AGW channel of the LAI coupling.

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“…In this sense, the biggest problem in the second atmospheric oscillation channel is that it is based on an ad-hoc assumption that there must be present some kind of precursory phenomena near the ground surface. There have been published a few papers that there occur some precursory ground movements in possible association with EQs by analyzing the GPS data (Chen et al, 2011;Milillo et al, 2012). So, there are very lacking works on the correlations between the ionospheric perturbations and ground effects before an EQ.…”

Section: Introductionmentioning

confidence: 99%

A note on the correlation of seismo-ionospheric perturbations with ground motions as deduced from F-net seismic observations

Endo

Kasahara

Hobara

et al. 2013

JAE

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The purpose of this paper is to try to find any correlation between the ionospheric perturbation as detected by subionospheric VLF/LF propagation and ground motions as detected by wideband seismic observations (so-called F-net). Two huge earthquakes are chosen for our analysis; (1) Niigata-chuetsu-oki earthquake on July 16, 2007 and (2) Iwate-nairiku-nambu earthquake on June 13, 2008. The AW(acoustic wave, period=1-10 min) and AGW(atmospheric gravity wave, period=10-100 min) components in the ground motions are compared with the ionospheric perturbation. It is found that the ground motions in the AGW and AW ranges are enhanced as compared with the backgrounds when the lower ionosphere is perturbed, which might be a possible source of ionospheric perturbation. Though the number of events is only two, this correlation may lend a support to the atmospheric oscillation hypothesis of the lithosphereionosphere coupling due to some precursory ground effect.

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Variation of Altitude Observed on the Occasion of the Tohoku Earthquake (M = 9.0) Occurred on March 11, 2011

Cited by 3 publications

References 7 publications

The observation of Doppler shifts of subionospheric LF signal in possible association with earthquakes

The observation of Doppler shifts of subionospheric LF signal in possible association with earthquakes

An evidence on the lithosphere-ionosphere coupling in terms of atmospheric gravity waves on the basis of a combined analysis of surface pressure, ionospheric perturbations and ground-based ULF variations

A note on the correlation of seismo-ionospheric perturbations with ground motions as deduced from F-net seismic observations

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