Acoustic Resonance of the Atmospheric at 3.7 Hz

Tahira, Makoto

doi:10.1175/1520-0469(1995)052<2670:arotaa>2.0.co;2

Cited by 37 publications

(37 citation statements)

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“…The peaks have a period close to the major modes of the resonance that has been predicted theoretically (e.g., Tahira, 1995;Lognonne et al, 1998;Nishida et al, 2000;Shinagawa et al, 2007), and their magnetic effects, through the ionospheric dynamo process, have also been expected since 2004 Sumatra earthquake (Iyemori et al, 2005).…”

Section: Summary and Discussionsupporting

confidence: 65%

Barometric and magnetic observations of vertical acoustic resonance and resultant generation of field-aligned current associated with earthquakes

et al. 2013

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Three rare occasions are introduced, where the excitation of vertical acoustic resonance between the ground and the ionosphere, and the resultant generation of a field-aligned current, just after earthquakes are observationally confirmed. In the case of two inland earthquakes, barometric observations very close to the epicenters (i.e., only 30 km apart) were available, and they showed a sharp spectral peak which appeared within one hour after the origin time and lasted a few hours. The observed periods of the spectral peaks around 260 seconds are close to the period of the theoretically-expected fundamental mode of the resonance. On the other hand, magnetic observations on the ground showed a dominant period at 220-230 seconds which corresponds to the first overtone among theoretically-expected major resonance peaks. In the third case, i.e., during the 2010 Chile earthquake, a long-period magnetic oscillation in the east-west direction, which has two major resonance periods at 265 and 190-195 seconds, was observed on the night-side magnetic dip equator in Peru, where the distance is more than 2600 km from the epicenter, under a very quiet geomagnetic condition. The oscillation was interpreted as the effect of field-aligned current generated through a dynamo process in the ionosphere over the epicenter caused by the resonance.

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Section: Summary and Discussionsupporting

confidence: 65%

Barometric and magnetic observations of vertical acoustic resonance and resultant generation of field-aligned current associated with earthquakes

et al. 2013

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“…This mechanism is generated by the vertical wind oscillation caused by the atmospheric duct resonance set up by the earthquake. During the earthquake, vertical ground motions cause atmospheric waves to propagate upward to the ionosphere, and then part of the wave energy is reflected back to the ionospheric E-layer to form a duct resonance (Tahira, 1995). The result is a vertical oscillation in the atmosphere with a resonance period of 4.8 min in the ionospheric E-layer, which is generated by the dynamo current.…”

Section: Observation Of Geomagnetic Disturbancesmentioning

confidence: 99%

Ionospheric and geomagnetic disturbances during the 2005 Sumatran earthquakes

Hasbi

Momani

Ali

et al. 2009

Journal of Atmospheric and Solar-Terrestrial Physics

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“…In addition to the magnitude of the earthquake and focal depth, there is some evidence that the earthquake focal mechanism , atmospheric acoustic resonance conditions (e.g. at 3.7 and 4.4 mH z , Nishida et al, 2000;Rolland et al, 2013;Sunil et al, 2015;Tahira, 1995), directivity and apparent velocity (Heki and Ping, 2005), geomagnetic latitude, and other factors, can influence the intensity of ionospheric responses. While some of these aspects are addressed by Cahyadi and Heki (2015) using 21 earthquakes between M w 6.6 and 9.2, TEC response amplitudes during quiet and disturbed geomagnetic conditions have been compiled by Perevalova et al (2014), which can serve as ready reference to seismo-ionospheric studies.…”

Section: Introductionmentioning

confidence: 99%