Ionospheric disturbances triggered by the 11 March 2011M9.0 Tohoku earthquake

Abstract

[1] An earthquake of magnitude 9.0 occurred near the east coast of Honshu (Tohoku area), Japan, producing overwhelming Earth surface motions and inducing devastating tsunamis, which then traveled into the ionosphere and significantly disturbed the electron density within it (hereafter referred to as seismotraveling ionospheric disturbances (STIDs)). The total electron content (TEC) derived from nationwide GPS receiving networks in Japan and Taiwan is employed to monitor STIDs triggered by seismic and tsunami waves of the Tohoku earthquake. The STIDs first appear as a disk-shaped TEC increase about 7 min after the earthquake occurrence centered at about 200 km east of the epicenter, near the west edge of the Japan Trench. Fast propagating disturbances related to Rayleigh waves quickly travel away from the epicenter along the main island of Japan with a speed of 2.3-3.3 km/s, accompanied by sequences of concentric circular TEC wavefronts and followed by circular ripples (close to a tsunami speed of about 720-800 km/h) that travel away from the STID center. These are the most remarkable STIDs ever observed where signatures of Rayleigh waves, tsunami waves, etc., simultaneously appear in the ionosphere.

Seismo-traveling ionospheric disturbances of ionograms observed during the 2011 M w 9.0 Tohoku Earthquake

“…Artru et al, 2004; Heki and Ping, 2005;Liu et al, 2010). Therefore, the speed of 900 m/s suggests the 2 nd STID being related to AGWs mainly traveling in the ionosphere of about 200 km altitude, which is close to the value of 1032-1045 m/s given by Liu et al (2011) and the 1 km/s (1000 m/s) given by Rolland et al (2011).…”

“…It is essential to find whether this assumption is reasonable and appropriate. Liu et al (2011) report that STIDs of the GPS TEC first appear near the epicenter about 7 minutes after the Tohoku Earthquake onset, while Tsai et al (2011) find that the STIDs in the GPS TEC triggered by the Rayleigh waves appear 7-8 minutes after the earthquake occurrence. Maruyama et al (2011) further cross-compare concurrent/co-located GPS TECs and ionograms recorded by the 4 ionosondes in Japan during the Tohoku Earthquake.…”

Atmospheric gravity waves due to the Tohoku‐Oki tsunami observed in the thermosphere by GOCE

“…Due to kinetic energy conservation and to the exponential density decrease in the atmosphere, these waves are amplified and generate significant perturbations in the thermosphere/ionosphere system [Peltier and Hines, 1976]. Electron density perturbations due to these gravity waves were observed in GPS data [Artru et al, 2005;Rolland et al, 2010;Galvan et al, , 2012Occhipinti et al, 2013], ionospheric doppler sounders [Liu et al, 2006[Liu et al, , 2011, and ionospheric correction of altimetric satellites [Occhipinti et al, 2006]. Recently, the effect of these gravity waves on the nightside airglow was modeled [Hickey et al, 2010] and observed [Makela et al, 2011], adding a new way to detect tsunami propagation in the thermosphere.…”

On the Origin of Mega-thrust Earthquakes

“…Liu et al 2011;Tsugawa et al 2011), may provide important opportunities to understand the deformation processes before the occurrence of the mega-thrust earthquakes.…”