Terr. Atmos. Ocean. Sci., Vol. 19, No. 6, 751-759, December 2008

doi: 10.3319/TAO.2008.19.6.751(PT)

Seismo-Ionospheric Precursors of the 26 December 2006 M7.0 Pingtung Earthquake Doublet


Jann-Yenq Liu1,2,*, Sen-Wen Chen1, Yao-Chun Chen1, Horng-Yuan Yen3, Chung-Pai Chang2,3, Wen-Yen Chang4, Lung-Chih Tsai2,1, Chia-Hung Chen1, Wen-Hsi Yang1


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

2 Center for Space and Remote Sensing Research, National Central University , Chung-Li , Taiwan

3 Department of Earth Science and Institute of Geophysics , National Central University , Chung-Li , Taiwan

4 Department of Natural Science, National Science Council, Taipei , Taiwan



Anetwork of ground-based GPS receivers, an ionosonde, and a Doppler sounding system have been employed to monitor the total electron content (TEC), electron density, and vertical motion of the ionosphere above Taiwan. Two M 7.0 offshore earthquakes occurred near Pingtung, the most southern county of Taiwan, on 26 December 2006. Analysis has revealed that the ionospheric TEC and F2-pear electron density (NmF2) surrounding the epicenters of the events decreased abnormally in the afternoon of the fourth day before the earthquakes, and quasi 3-minute fluctuations of pronounced vertical motion in the ionosphere also appeared over the last two days prior to the earthquakes. This is for the first time the pre-earthquake fluctuation signatures in the ionosphere being reported.

Keywords: Seismo-ionospheric precursor, Ionosphere, Total electron content, NmF2, Doppler sounding system

Citation: Liu, J, . Y.S. W. Chen, Y. C. Chen, H. Y. Yen, C. P. Chang, W. Y. Chang, L. C. Tsai, C. H. Chen, and W. H. Yang, 2008: Seismo-ionospheric precursors of the 26 December 2006 M 7.0 Pingtung earthquake doublet. Terr. Atmos. Ocean. Sci., 19, 751-759, doi: 10.3319/TAO.2008.19.6.751(PT)