HF-Doppler observations of acoustic waves excited by the Urakawa-Oki earthquake on 21 March 1982

Tanaka, Teruya; Ichinose, Takumi; Okuzawa, Takashi; Shibata, Takashi; Sato, Yukinori; Nagasawa, Chikao; Ogawa, Teiichiro

doi:10.1016/0021-9169(84)90150-8

Cited by 66 publications

(59 citation statements)

References 17 publications

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“…It is a subject for future studies. Tanaka et al (1984) discussed the characteristics of coseismic ionospheric disturbances with a period of a few minutes using four HF Doppler receivers in Japan. They determined a horizontal propagation velocity of 3.5 to 3.9 km/s.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…To the best of our knowledge, this is the first paper to report on traveling ionospheric disturbances with a propagation velocity range of a few km/s. Tanaka et al (1984) and Ducic et al (2003) did not consider the velocity dispersive signatures of the traveling ionospheric disturbances. This might be because their events were much smaller, compared with the present case, to enable the investigation of later disturbances, or because the sensitivity of their instruments was not high enough.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…Coseismic ionospheric disturbances have been studied using various kinds of instruments such as a GPS receiver network (e.g., Ducic et al, 2003;Otsuka et al, 2006), an HF Doppler system (e.g., Tanaka et al, 1984), magnetometers (e.g., Iyemori et al, 1996) and a mixture of some of these (e.g., Ogawa et al, 1982). Most papers reported that the disturbances propagated away from the epicenter with a velocity of 2-4 km/s, corresponding to the propagation of the Earth's surface waves (Rayleigh waves).…”

Section: Introductionmentioning

confidence: 99%

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Propagation of large amplitude ionospheric disturbances with velocity dispersion observed by the SuperDARN Hokkaido radar after the 2011 off the Pacific coast of Tohoku Earthquake

et al. 2011

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Ionospheric responses to the 2011 off the Pacific coast of Tohoku Earthquake are studied using the SuperDARN Hokkaido radar, which is located at (43.5• N, 143.6• E) and which monitors the ionosphere over a wide horizontal area. The radar observed an oscillation of the vertical motion of the ionosphere with a period of about 1 to 2 min. The disturbance propagated northward, away from the epicenter with the velocity of about 6.2, 4.5, 3.9 and 3.5 km/s. The latter three values are basically consistent with the propagation of the Earth's surface waves reported in several previous studies. The propagation velocities decreased with time, which has not been reported in previous studies for this propagation velocity range. The peak-to-peak amplitudes of Doppler velocities of ground/sea scatter echoes observed by the radar were up to 200 m/s, which is considerably larger than previously-reported values using HF Doppler measurements, although they are not extremely large for this historical earthquake (M = 9.0). This is the first time that ionospheric data have been obtained with high temporal (8 s) and spatial (22.5 km) resolutions following a giant earthquake, which enables us to discuss the detailed characteristics of the propagation of coseismic ionospheric disturbances.

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Section: Discussion and Summarymentioning

confidence: 99%

Section: Discussion and Summarymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Propagation of large amplitude ionospheric disturbances with velocity dispersion observed by the SuperDARN Hokkaido radar after the 2011 off the Pacific coast of Tohoku Earthquake

et al. 2011

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“…As the excited infrasound signals propagate upward, their amplitudes increase due to the conservation of momentum in the density-rarefied atmosphere (e.g., Chum et al, 2012;Maruyama and Shinagawa, 2014). Infrasound signals with periods longer than ∼ 15 s reach ionospheric altitudes (Tanaka et al, 1984) and interact with ions through neutralion collisions. At ionospheric altitudes, sound speed is 500 to 1000 m s −1 , yielding vertical wavelengths of 7.5 to 50 km.…”

Section: Introductionmentioning

confidence: 99%

Interpretation of deformed ionograms induced by vertical ground motion of seismic Rayleigh waves and infrasound in the thermosphere

2016

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Abstract. The vertical ground motion of seismic surface waves launches acoustic waves into the atmosphere and induces ionospheric disturbances. Disturbances due to Rayleigh waves near the short-period Airy phase appear as wavy fluctuations in the virtual height of an ionogram and have a multiple-cusp signature (MCS) when the fluctuation amplitude is increased. An extremely developed MCS was observed at Kazan, Russia, after the 2010 M 8.8 Chile earthquake. The ionogram exhibited steep satellite traces for which the virtual heights increased rapidly with frequency starting near the top of cusps and continuing for 0.1-0.2 MHz. This complicated ionogram was analyzed by applying a ray tracing technique to the radio wave propagation in the ionosphere that was perturbed by acoustic waves. Acoustic wavefronts were inclined by the effects of finite Rayleigh wave velocity and sound speed in the thermosphere. The satellite echo traces were reproduced by oblique returns from the inclined wavefronts, in addition to the nearly vertical returns that are responsible for the main trace.

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“…Using ionograms recorded by MF/HF (median/high frequency) ionosondes and frequency shifts probed by HF Doppler sounders, scientists have observed STIDs triggered by strong earthquakes (Davies and Baker 1965;Leonard and Barnes 1965;Row 1967;Yuen et al 1969;Tanaka et al 1984;Blanc 1985;Artru et al 2004;Liu et al 2006a). Due to limited numbers and/or short distances among stations of ionosonde or Doppler sounding networks, it is rather difficult to study the propagation of STIDs in detail.…”

Section: Introductionmentioning

confidence: 99%

Seismo-Traveling Ionospheric Disturbances Triggered by the 12 May 2008 M 8.0 Wenchuan Earthquake

Liu¹,

Sun²,

Tsai³

et al. 2012

Terr. Atmos. Ocean. Sci.

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A network of 6 ground-based GPS receivers in East Asia was employed to study seismo-traveling ionospheric disturbances (STIDs) triggered by an M 8.0 earthquake which occurred at Wenchuan on 12 May 2008. The network detected 5 STIDs on the south side of the epicenter area. A study on the distances of the detected STIDs to the epicenter versus their associated traveling times shows that the horizontal speed is about 600 m s -1 . Applying the circle method, we find that the 5 circles intercept at a point right above the epicenter when the horizontal speed of 600 m s -1 is given. Global searches of the ray-tracing and the beam-forming techniques confirm that the STIDs are induced by vertical motions in the Earth's surface during the Wenchuan Earthquake.

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HF-Doppler observations of acoustic waves excited by the Urakawa-Oki earthquake on 21 March 1982

Cited by 66 publications

References 17 publications

Propagation of large amplitude ionospheric disturbances with velocity dispersion observed by the SuperDARN Hokkaido radar after the 2011 off the Pacific coast of Tohoku Earthquake

Propagation of large amplitude ionospheric disturbances with velocity dispersion observed by the SuperDARN Hokkaido radar after the 2011 off the Pacific coast of Tohoku Earthquake

Interpretation of deformed ionograms induced by vertical ground motion of seismic Rayleigh waves and infrasound in the thermosphere

Seismo-Traveling Ionospheric Disturbances Triggered by the 12 May 2008 M 8.0 Wenchuan Earthquake

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