Dependence of waveform of near-field coseismic ionospheric disturbances on focal mechanisms

Astafyeva, Elvira; Heki, K.

doi:10.1186/bf03353206

Cited by 95 publications

(95 citation statements)

References 23 publications

(40 reference statements)

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“…However, it is important to note that the ground perturbation associated with an earthquake exhibits greater complexity than a simple vertical acceleration at the surface (such as our "Directive" source models). Astafyeva and Heki [2009] note, too, ionospheric signature dependencies on the seismic disturbance, depending on the nature of the faults. Future theoretical and modeling studies can provide new insight into the response dependence on source characteristics.…”

Section: Consistency Of Modeled Tec Responses With Observed Eventsmentioning

confidence: 98%

Ionospheric response to infrasonic‐acoustic waves generated by natural hazard events

2015

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Recent measurements of GPS‐derived total electron content (TEC) reveal acoustic wave periods of ∼1–4 min in the F region ionosphere following natural hazard events, such as earthquakes, severe weather, and volcanoes. Here we simulate the ionospheric responses to infrasonic‐acoustic waves, generated by vertical accelerations at the Earth's surface or within the lower atmosphere, using a compressible atmospheric dynamics model to perturb a multifluid ionospheric model. Response dependencies on wave source geometry and spectrum are investigated at middle, low, and equatorial latitudes. Results suggest constraints on wave amplitudes that are consistent with observations and that provide insight on the geographical variability of TEC signatures and their dependence on the geometry of wave velocity field perturbations relative to the ambient geomagnetic field. Asymmetries of responses poleward and equatorward from the wave sources indicate that electron perturbations are enhanced on the equatorward side while field aligned currents are driven principally on the poleward side, due to alignments of acoustic wave velocities parallel and perpendicular to field lines, respectively. Acoustic‐wave‐driven TEC perturbations are shown to have periods of ∼3–4 min, which are consistent with the fraction of the spectrum that remains following strong dissipation throughout the thermosphere. Furthermore, thermospheric acoustic waves couple with ion sound waves throughout the F region and topside ionosphere, driving plasma disturbances with similar periods and faster phase speeds. The associated magnetic perturbations of the simulated waves are calculated to be observable and may provide new observational insight in addition to that provided by GPS TEC measurements.

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Section: Consistency Of Modeled Tec Responses With Observed Eventsmentioning

confidence: 98%

Ionospheric response to infrasonic‐acoustic waves generated by natural hazard events

2015

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“…While the electric field related perpendicular transport will manifest along the entire field line (as the field line is nearly equipotential), wind transport parallel to the magnetic field line can be highly localized. Thus all the earlier works on seismic infrasound effects in the ionosphere have considered only the wind forcing parallel to the magnetic field lines (Artru et al, 2004;Astafyeva and Heki, 2009;Chum et al, 2012). Recently, Huba et al (2015) have considered the magnetic field perpendicular component of the vertical wind perturbation to generate electric field.…”

Section: Ionospheric Response To Seismic Infrasoundmentioning

confidence: 99%

Simulating the dependence of seismo-ionospheric coupling on the magnetic field inclination

et al. 2018

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Abstract. Infrasound generated during a seismic event upon reaching the ionospheric heights possesses the ability to perturb the ionosphere. Detailed modelling investigation considering 1-D dissipative linear dynamics, however, indicates that the magnitude of ionospheric perturbation strongly depends on the magnetic field inclination. Physics-based SAMI2 model codes have been utilized to simulate the ionosphere perturbations that are generated due to the action of the vertical wind perturbations associated with the seismic infrasound. The propagation of the seismic energy and the vertical wind perturbations associated with the infrasound in the model has been considered to be symmetric about the epicentre in the north-south directions. Ionospheric response to the infrasound wind, however, has been highly asymmetric in the model simulation in the north-south directions. This strong asymmetry is related to the variation in the inclination of the Earth's magnetic field north and south of the epicentre. Ionospheric monitoring generally provides an efficient tool to infer the crustal propagation of the seismic energy. However, the results presented in this paper indicate that the mapping between the crustal process and the ionospheric response is not a linear one. These results also imply that the lithospheric behaviour during a seismic event over a wide zone in low latitudes can be estimated through ionospheric imaging only after factoring in the magnetic field geometry.Keywords. Atmospheric composition and structure (pressure density and temperature) -history of geophysics (atmospheric sciences) -ionosphere (ionosphere-atmosphere interactions)

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“…The resonance is predicted to be limited to the vicinity of the source region, because it was established by the vertical reflection of the acoustic wave. Besides the periodic fluctuation, several types of ionospheric variations after earthquakes have been reported (e.g., Afraimovich et al, 2001;Heki and Ping, 2005;Otsuka et al, 2006;Astafyeva and Heki, 2009).…”

Section: Introductionmentioning

confidence: 99%

Acoustic resonance and plasma depletion detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake

et al. 2011

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Two-dimensional structures of the ionospheric variations generated by the acoustic resonance between the ground surface and the lower thermosphere was observed for the first time near the epicenter after the M 9.0 Tohoku earthquake on March 11, 2011. A short-period oscillation of total electron content was observed by a GPS receiver array after the earthquake for four hours in the vicinity of the epicenter. It was centered in the east of the epicenter where the tsunami was estimated to commence. The frequency of the dominant mode of the oscillation was 4.5 mHz, 222 seconds of period, while there were minor oscillations whose frequency were 3.7 mHz and 5.3 mHz. These periods are consistent with the periods of the acoustic resonance between the ground surface and the lower thermosphere, predicted by a numerical model. The amplitude of the TEC oscillation showed a gradual change of the amplitude. The two-dimensional distributions of TEC variations generated by this resonance had wave frontal structures that extended from northwest to southeast. The resonant oscillation of the TEC was accompanied by a depletion of TEC whose duration was about 60 minutes. The area of this depletion also centered on the epicenter.

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Dependence of waveform of near-field coseismic ionospheric disturbances on focal mechanisms

Cited by 95 publications

References 23 publications

Ionospheric response to infrasonic‐acoustic waves generated by natural hazard events

Ionospheric response to infrasonic‐acoustic waves generated by natural hazard events

Simulating the dependence of seismo-ionospheric coupling on the magnetic field inclination

Acoustic resonance and plasma depletion detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake

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