Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements

J. Y. Liu, Y. J. Chuo, S. J. Shan, Y. B. Tsai, Y. I. Chen, S. A. Pulinets, S. B. Yu

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In this paper we examine pre-earthquake ionospheric anomalies by the total electron content (TEC) derived from a ground-based receiver of the Global Positioning System (GPS). A 15-day running median of the TEC and the associated inter-quartile range (IQR) are utilized as a reference for identifying abnormal signals during all of the 20M≧6.0 earthquakes in the Taiwan area from September 1999 to December 2002. Results show that the pre-earthquake ionospheric anomalies appear during 18:00-22:00 LT (LT=UT+8h) within 5 days prior to 16 of the 20 M≧6.0 earthquakes. This success rate of 80% (=16/20%) suggests that the GPS TEC is useful to register pre-earthquake ionospheric anomalies appearing before large earthquakes.

Original languageEnglish
Pages (from-to)1585-1593
Number of pages9
JournalAnnales Geophysicae
Issue number5
StatePublished - 2004


  • Ionosphere (ionospheric disturbances; ionosphere-atmosphere interactions)


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