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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS010 Oral Presentation 2073 Precursors in ionospheric GPS TEC of the 26 December 2004 M9.3 Sumatra earthquake Prof. Jann-Yenq Liu National Central University ISS, National Central University IAGA Yuh-Ing Chen An M9.3 earthquake, the largest one in the recent 5 decades, occurred in Sumatra Indonesia at 00:58:53 UT (universal time) on 26 December 2004. A time sequence of global ionosphere maps (GIMs) derived from worldwide ground-based receivers of the global positioning system (GPS) is used to monitor changes of the ionospheric total electron content (TEC). It is found that near the epicenter the ionospheric electron density anomalously decreases in the afternoon period on 21 December 2004 which is day 5 prior to the earthquake. The spatial distributions of the decreased anomalies further indicate that the ionospheric fountain is significantly disturbed and electrodynamics is important. Keywords: seismo ionospheric, gps, tec

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS010 Oral Presentation 2074 Review of pre-seismic lithosphere - atmosphere - ionosphere coupling study Dr. Masashi Kamogawa Department of Physics Tokyo Gakugei University Pre-seismic anomalous states in the atmosphere and ionosphere as well as those in the telluric currents and ultra-low frequency electromagnetic waves have been reported since the 1970s. These pre-seismic phenomena have not yet been universally accepted, partly because the low occurrence frequency of large earthquakes has hindered establishing their statistical significance. Recent achievements in this respect, however, seem to be highly encouraging for promoting further studies on the pre-seismic lithosphere-atmosphere-ionosphere (LAI) coupling. Liu et al. (JGR, 2006) constructed a set of quantitative definitions for ionospheric anomalies (depression of foF2) and examined the statistical correlation between thus defined ionospheric anomalies and all the Taiwan M>=5 earthquakes (184 in number) during the period 1994-1999. The results indicated that anomalies appeared within 5 days before the earthquakes. Examining the validity of the pre-seismic anomalous transmission of VHF electromagnetic waves beyond the line-of-sight, Fujiwara and Kamogawa et al. (GRL, 2004) statistically demonstrated the existence of atmospheric anomalies lasting for a few minutes to several hours before earthquakes. They found that the anomalies were significantly enhanced within 5 days before M>=4.8 earthquakes. If the pre-seismic atmospheric - ionospheric anomalies are real, some phenomena causing them should be detectable on the ground. If such causal phenomena are identified, the concept of lithosphere - atmosphere - ionosphere coupling (LAI coupling) will be greatly strengthened. Possible mechanisms for energy-transport channels from the lithosphere to the atmosphere-ionosphere are summarized as follows: First, the atmospheric electric field generated on/near the ground surface during the pre-seismic period may cause the ionospheric anomalies. Such an atmospheric electric field may be caused by ions generated from radon emissions. Actually, a number of reports have been published for pre-seismic radon emissions. However, such pre-seismic electric fields on the ground followed by pre-seismic ionospheric anomalies have not yet been observed. Alternatively, it has been proposed that atmospheric gravity waves propagate up to and disturbs the ionosphere before earthquakes. The proposed sources of the gravity waves are long-period ground oscillations or thermal anomalies. This proposed linkage is inferred from the observations of co-seismic ground vibrations and tsunami exciting atmospheric gravity waves which propagate into ionosphere. However, there is no report of pre-seismic long-period ground oscillations being detected, even by sensitive superconducting gravimeters. Although some reports claim the existence of pre-seismic rises of temperature, infrared radiation, and surface latent heat flux, it is difficult to explain how such anomalies disturb the ionosphere through the atmosphere. As discussed in this abstract, the cause and effect relationships may still be unestablished but pre-seismic atmospheric-ionospheric anomalies do exist and searching for the lithospheric connection remains an important research endeavor. Keywords: earthquake, ionosphere, atmosphere

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