Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements
1Institute of Space Science, National Central University, Taiwan
2Center for Space and Remote Sensing Research, National Central University, Taiwan
3Department of Information Management, Ling-Tung College, Taiwan
4Institute of Geophysics, National Central University, Taiwan
5Institute of Statistics, National Central University, Taiwan
6Institute of Geophysics, National Autonomous University of Mexico, Mexico
7Institute of Earth Sciences, Academia Sinica, Taiwan
Abstract. 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 18:00–22:00LT (LT=UT+8h) within 5 days prior to 16 of the 20M≥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.
Key words. Ionosphere (ionospheric disturbances; ionosphere-atmosphere interactions)
Liu, J. Y., Chuo, Y. J., Shan, S. J., Tsai, Y. B., Chen, Y. I., Pulinets, S. A., and Yu, S. B.: Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements, Ann. Geophys., 22, 1585-1593, doi:10.5194/angeo-22-1585-2004, 2004.