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GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L02103, doi:10.1029/2005GL023963, 2006

Giant ionospheric disturbances excited by the M9.3 Sumatra earthquake of 26 December 2004

J. Y. Liu

Institute of Space Science, National Central University, Chung-Li, Taiwan


Y. B. Tsai

Institute of Geophysics, National Central University, Chung-Li, Taiwan


S. W. Chen

Institute of Space Science, National Central University, Chung-Li, Taiwan


C. P. Lee

Institute of Geophysics, National Central University, Chung-Li, Taiwan


Y. C. Chen

Institute of Space Science, National Central University, Chung-Li, Taiwan


H. Y. Yen

Institute of Geophysics, National Central University, Chung-Li, Taiwan


W. Y. Chang

Institute of Geophysics, National Central University, Chung-Li, Taiwan


C. Liu

Institute of Geophysics, National Central University, Chung-Li, Taiwan


Abstract

An Mw 9.3 earthquake originated in the Indian Ocean off the western coast of northern Sumatra at 00:58:53 Universal Time (UT) on 26 December 2004. Two giant ionospheric disturbances at 01:19 and 04:10 UT are observed by a network of digital Doppler sounders in Taiwan. The first disturbance excited mainly by Rayleigh waves, which consists of a packet of short-period Doppler shift variations, results in vertical ionospheric fluctuations with a maximum velocity of about 70 m/s and displacement of about 200 m. The second disturbance, in a W-shaped pulse propagating at a horizontal speed of 360 ± 70 m/s, is attributable to coupling of the atmospheric gravity waves (AGW) excited by broad crustal uplift together with the following big tsunami waves around the earthquake source zone. The accompanying ionosonde data suggest that the AGW in the atmosphere may have caused the ionosphere to move up and down by about 40 km.

Received 1 July 2005; accepted 6 December 2005; published 21 January 2006.

Index Terms: 2435 Ionosphere: Ionospheric disturbances; 2499 Ionosphere: General or miscellaneous; 7299 Seismology: General or miscellaneous.

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Citation: Liu, J. Y., Y. B. Tsai, S. W. Chen, C. P. Lee, Y. C. Chen, H. Y. Yen, W. Y. Chang, and C. Liu (2006), Giant ionospheric disturbances excited by the M9.3 Sumatra earthquake of 26 December 2004, Geophys. Res. Lett., 33, L02103, doi:10.1029/2005GL023963.