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Ann. Geophys., 22, 1585-1593, 2004
www.ann-geophys.net/22/1585/2004/
© European Geosciences Union 2004
Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements
J. Y. Liu1,2, Y. J. Chuo3, S. J. Shan1, Y. B. Tsai4, Y. I. Chen5, S. A. Pulinets6, and S. B. Yu7
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)
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