The use of subionospheric VLF∕LF propagation for the study of lower ionospheric perturbations associated with earthquakes

2010 ◽  
Author(s):  
M. Hayakawa ◽  
Sandip K. Chakrabarti
Keyword(s):  
Ionospheric Perturbations

Ionospheric perturbations before Pu’er earthquake observed on DEMETER

2008 ◽  
Vol 21 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Rong Zhu ◽  
Dong-mei Yang ◽  
Feng Jing ◽  
Jun-ying Yang ◽  
Xin-yan Ouyang
Keyword(s):  
Ionospheric Perturbations ◽  
Pu’Er Earthquake

scholarly journals Ionospheric response to magnetar flare: signature of SGR J1550–5418 on coherent ionospheric Doppler radar

2017 ◽  
Vol 35 (3) ◽  
pp. 345-351 ◽  
Author(s):  
Ayman Mahrous
Keyword(s):  
Total Electron Content ◽  
Large Scale ◽  
Doppler Radar ◽  
Ionospheric Disturbance ◽  
Eastern Mediterranean ◽  
Small Scale ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Perturbations ◽  
Onset Phase

Abstract. This paper presents observational evidence of frequent ionospheric perturbations caused by the magnetar flare of the source SGR J1550–5418, which took place on 22 January 2009. These ionospheric perturbations are observed in the relative change of the total electron content (ΔTEC/Δt) measurements from the coherent ionospheric Doppler radar (CIDR). The CIDR system makes high-precision measurements of the total electron content (TEC) change along ray-paths from ground receivers to low Earth-orbiting (LEO) beacon spacecraft. These measurements can be integrated along the orbital track of the beacon satellite to construct the relative spatial, not temporal, TEC profiles that are useful for determining the large-scale plasma distribution. The observed spatial TEC changes reveal many interesting features of the magnetar signatures in the ionosphere. The onset phase of the magnetar flare was during the CIDR's nighttime satellite passage. The nighttime small-scale perturbations detected by CIDR, with ΔTEC/Δt  ≥  0.05 TECU s−1, over the eastern Mediterranean on 22 January 2009 were synchronized with the onset phase of the magnetar flare and consistent with the emission of hundreds of bursts detected from the source. The maximum daytime large-scale perturbation measured by CIDR over northern Africa and the eastern Mediterranean was detected after ∼ 6 h from the main phase of the magnetar flare, with ΔTEC/Δt  ≤  0.10 TECU s−1. These ionospheric perturbations resembled an unusual poleward traveling ionospheric disturbance (TID) caused by the extraterrestrial source. The TID's estimated virtual velocity is 385.8 m s−1, with ΔTEC/Δt  ≤  0.10 TECU s−1.

scholarly journals Mapping the Impact of Non-Tectonic Forcing mechanisms on GNSS measured Coseismic Ionospheric Perturbations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mala S. Bagiya ◽  
A. S. Sunil ◽  
Lucie Rolland ◽  
Srinivas Nayak ◽  
M. Ponraj ◽  
...  
Keyword(s):  
Near Field ◽  
Electron Content ◽  
Combined Effects ◽  
Total Electron ◽  
Ionospheric Perturbations ◽  
Source Characteristics ◽  
Atmospheric Wave ◽  
Forcing Mechanisms ◽  
The Impact ◽  
Tectonic Forcing

AbstractGlobal Navigation Satellite System (GNSS) measured Total Electron Content (TEC) is now widely used to study the near and far-field coseismic ionospheric perturbations (CIP). The generation of near field (~500–600 km surrounding an epicenter) CIP is mainly attributed to the coseismic crustal deformation. The azimuthal distribution of near field CIP may contain information on the seismic/tectonic source characteristics of rupture propagation direction and thrust orientations. However, numerous studies cautioned that before deriving the listed source characteristics based on coseismic TEC signatures, the contribution of non-tectonic forcing mechanisms needs to be examined. These mechanisms which are operative at ionospheric altitudes are classified as the i) orientation between the geomagnetic field and tectonically induced atmospheric wave perturbations ii) orientation between the GNSS satellite line of sight (LOS) geometry and coseismic atmospheric wave perturbations and iii) ambient electron density gradients. So far, the combined effects of these mechanisms have not been quantified. We propose a 3D geometrical model, based on acoustic ray tracing in space and time to estimate the combined effects of non-tectonic forcing mechanisms on the manifestations of GNSS measured near field CIP. Further, this model is tested on earthquakes occurring at different latitudes with a view to quickly quantify the collective effects of these mechanisms. We presume that this simple and direct 3D model would induce and enhance a proper perception among the researchers about the tectonic source characteristics derived based on the corresponding ionospheric manifestations.

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