Image by NASA/JPL-Caltech. Caption by Michael Carlowicz.
The 2011 earthquake and tsunami in Japan had so many potent effects, but one of the most unusual is the one it had on the upper atmosphere. The ripples moving through the landscape and the seascape created ripples in the ionosphere, a layer above 85 kilometers (50 miles) in altitude where molecules are broken into electrons and ions by the Sun’s radiation.
This image—a still-frame from an animation (linked here)—shows how waves of energy from the earthquake and tsunami propagated up to the edge of space and disturbed the density of the electrons in the ionosphere. The image is based on sophisticated modeling of the distortion of radio signals between Global Positioning System (GPS) satellites and ground receivers. The map shows changes in the Total Electron Content (TEC) in the ionosphere.
The earthquake created acoustic and Rayleigh waves that moved up into the ionosphere within 10 minutes after the quake. Similarly, the motion of the tsunami also disturbed the atmosphere, creating gravity waves that took 30 to 40 minutes to reach the ionosphere. The gravity waves matched the horizontal speed of the tsunami, roughly 200 to 300 meters per second. Provoked by both the quake and the tsunami, these atmospheric gravity waves traveled over and to the west of Japan, while the tsunami was stopped by the coast.
- Galvan, D.A., Komjathy, A., Hickey, M.P. and Mannucci, A.J. (2011) The 2009 Samoa and 2010 Chile tsunamis as observed in the ionosphere using GPS total electron content. Journal of Geophysical Research (Space Physics) 116, A06, 318.
- Occhipinti, G., Komjathy, A., and Lognonne, P. (2008, February) Tsunami Detection by GPS: How Ionospheric Observations Might Improve the Global Warning System. GPS World.
- Song, Y. T. (2007) Detecting tsunami genesis and scales directly from coastal GPS stations. Geophysical Research Letters, 34, L19,602.
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