地震發生時會使地表產生錯動甚至會引發海嘯。地震與海嘯的垂直震盪會以聲重波（Acoustic-gravity wave）的形式傳到電離層電漿產生移行電離層擾動現象(Seismo-traveling ionospheric disturbance,STID)。利用GPS訊號可得知電離層電漿全電子含量(total electron content,TEC)，了解電離層的擾動情形。
　2011年3月11日在日本東北外海發生一規模9.0的地震並引發海嘯，利用GPS觀測到的移行電離層擾動現象並配合小波分析（wavelet analysis），研究其地震與海嘯對電離層影響的時變頻譜特性，發現地震訊號較單純且週期較短，而海嘯訊號較複雜且週期較長。利用此方法分析不同事件如2004年南亞、2010年智利和2013所羅門地震等，了解更多地震和海嘯的時變頻譜特徵。而頻譜研究中發現，電離層中的海嘯擾動訊號有比海嘯早到的現象，有機會可發展成另一海嘯預警系統。

In this study, the seismo-traveling ionospheric disturbances (STIDs) in total electron content (TEC) generated by the 2011 Mw9.0 Great Tohoku earthquake at 05:46:23 UT on March 11, 2011, are investigated by using ground-based Global Positioning System (GPS) receiver networks. Not only triggered by seismic surface waves the STIDs formed by tsunami waves are clearly seen during the Tohoku earthquake event. A method of wavelet analysis is applied to investigate the spectral characters of STIDs induced by the seismic surface waves and the tsunami waves. Results show that the spectrum of STID resulting by surface waves reveals a single short period enhancement, while those by tsunami waves show multiple long-period responses. Additional events, including 2004 Sumatra(Mw 9.1), 2010 Chile(Mw 8.8) and 2013 Solomon(Mw 8.0) earthquakes, are investigated for the general spectral characteristics of seismic surface and tsunami waves. This results also shows that the arrival time of STID induced by surface waves is earlier than that by tsunami waves, which could be applied as the short-term tsunami warnings.

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