Two‐dimensional simulation of ionospheric variations in the vicinity of the epicenter of the Tohoku‐oki earthquake on 11 March 2011

Abstract

Unusual ionospheric variations were observed in the M9.0 Tohoku‐oki earthquake on 11 March 2011. Among various kinds of features in the ionosphere, significant depletion of total electron content (TEC) near the epicenter was observed after the earthquake. Although previous studies have suggested that the coseismic ionospheric variations are associated with atmospheric perturbation caused by vertical displacement of the sea surface, the mechanism of the TEC depletion has not been fully understood. In this paper, a two‐dimensional nonlinear nonhydrostatic compressible atmosphere‐ionosphere model is employed to investigate the ionospheric variations in the vicinity of the epicenter. The simulation results reveal that an impulsive pressure pulse produced by a sudden uplift of the sea surface leads to local atmospheric expansion in the thermosphere and that the expansion of the thermosphere combined with the effect of inclined magnetic field lines in the ionosphere causes the sudden TEC depletion above the epicenter region.

GNSS ionospheric seismology: Recent observation evidences and characteristics

“…The extremely dense TEC observation performed by the GEONET network clearly highlighted acoustic-gravity waves generated at the epicenter, acoustic waves coupled with Rayleigh wave, as well as gravity waves coupled with the propagation of the following tsunami (Occhipinti et al, 2013;Coisson et al, 2011). As clearly showed by Shinagawa et al (2013) and Rolland et al (2011), the TEC observations supplied by the dense GEONET network during the 11 March 2011 Tohoku earthquake and the 25 September 2003 Tokachi-Oki earthquake, provide a unique chance to investigate the seismic ionospheric disturbances related to the fault rupture in vicinity of the epicenter, as well as TEC perturbation related to the propagation of Rayleigh waves and tsunami in far-field. The Japanese GNSS network (GEONET) is denser with over 1200 continuous GNSS stations operated by Geographical Survey Institute (GSI) Japan.…”

Ionospheric signatures of the April 25, 2015 Nepal earthquake and the relative role of compression and advection for Doppler sounding of infrasound in the ionosphere

“…Good understanding of the ionospheric response to acoustic gravity waves excited by tsunamis could be potentially used in the tsunami early-warning systems since the infrasound waves propagate at larger velocities (~330 m/s) than tsunamis (~200 m/s at deep water). So, if the epicenter is sufficiently far in the sea, the related ionospheric disturbances can be detected before the tsunami arrival to the seacoast [Rolland et al 2010;Liu et al 2006b;Arai et al 2011;Shinagawa et al 2013]. It is, however, crucial to properly distinguish the co-seismic (co-tsunami) ionospheric disturbances from fluctuations caused by other kinds of forcing from below, e.g., acoustic gravity waves from severe weather systems , mountain waves, etc., and from above, e.g., geomagnetic and solar activity [Laštovička 2006;Liu et al 1996;Šindelářová et al 2009], and the meteorite falls [Brown et al 2013] and artificial re-entries [Yamamoto et al 2011].…”

Dynamics of vertical ionospheric inhomogeneities over Irkutsk during 06:00–06:20UT 11/03/2011 caused by Tohoku earthquake

“…There are many papers devoted to ionospheric precursors to earthquakes (Carter et al, 2013;Choi et al, 2012;Heki, 2011;Kamogawa and Kakinami, 2013;Le et al, 2013;Zolotov et al, 2012;Zhou et al, 2013) and to results of modeling of ionospheric effects Kherani et al, 2012;Makela et al, 2011;Matsumura et al, 2011;Shinagawa et al, 2013;Maruyama and Shinagawa, 2014), based on the data from these instruments.…”