Ionospheric foF2 and TEC Anomalous Days Associated with M &gt;= 5.0 Earthquakes in Taiwan during 1997-1999

Self Cite

AIP (advanced ionospheric probe) on board FORMOSAT-5 is a next version and advanced generation science payload of IPEI (ionospheric Plasma and Electrodynamics Instrument) on board ROCSAT-1 (i.e., FORMOSAT-1). We examine the ion density, ion temperature, and ion velocity probed by ROCSAT-1/IPEI, as well as the global ionospheric map (GIM) of the total electron content (TEC) derived by ground-based GPS receivers during the 31 March 2002 M6.8 Earthquake in Taiwan to determine whether FORMOSAT-5/AIP can be used to detect seismo-ionospheric precursors (SIPs). It is found that in the epicenter area, the GIM TEC significantly decreases 1 -5 days before the earthquake, while the ROCSAT-1/IPEI ion density significantly decreases and ion velocity in the downward direction anomalously increases. The anomalous decreases in the ROCSAT/IEPI ion density and the GIM TEC concurrently appear around the epicenter area 1 -5 days before the earthquake, which suggests that FORMOSAT-5/AIP can be employed to detect SIPs. Moreover, the increase in the downward velocity implies that a westward electric field generated during the preparation earthquake period is essential.

Section: Introductionmentioning

confidence: 99%

An observing system simulation experiment for FORMOSAT-5/AIP detecting seismo-ionospheric precursors

Liu¹,

Chao²

2017

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“…Since data obtained by the new observational facilities are still in the early stage, we concentrated our research efforts in the first two years on analyzing the existing data for past earthquakes. Detailed results are presented in several papers both in this special issue and elsewhere (Lee and Tsai 2004;Chan and Ma 2004;Chang et al 2004;Liu et al 2004b;). We will only give a summary below to highlight the results obtained so far.…”

Section: Preliminary Results Of Istep Programmentioning

confidence: 99%

Preminary Results of the iSTEP Program on Integrated Search for Taiwan Earthquake Precursors

Tsai¹,

Liu²,

Fong³

et al. 2004

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ABSTRACT1 Institute of Geophysics, National Central University, Chung-Li, Taiwan, ROC The predictability of earthquakes has been a hotly debated question in earthquake science for some time. The answer to which begs another question, "Are there credible earthquake precursors?" Intrigued by these questions and encouraged by instrumental observations of conspicuous ionospheric and geomagnetic disturbances before the disastrous 1999 Chi-Chi earthquake, we decided to undertake an integrated Search for Taiwan Earthquake Precursors, called the iSTEP program. The multidisciplinary program includes five major components aimed at identifying potential seismological, geomagnetic, geodetic and ionospheric precursors, and statistical testing of any identified precursors. Since the program's inception in April 2002, some encouraging preliminary results have been obtained. These includes precursory P wave travel-time changes six years before the Chi-Chi earthquake, identifiable geomagnetic changes two years before M ≥ 6 earthquakes, consistent ionospheric anomalies three days before M ≥ 5 earthquakes. We have also developed high-resolution radar interferometric methods for monitoring crustal deformation. A method for forecasting aftershock distribution on the basis of stress transfer has also been successfully tested on the Chi-Chi earthquake sequence. Aided by the newly installed geomagnetic and ionospheric networks we are hopeful about identifying more earthquake precursors and developing relevant physical mechanisms in the remaining two years of the iSTEP program.

“…Since the NmF2 is the greatest electron density in the ionosphere, Eq. (1) indicates that the NmF2 and TEC are highly correlated (also see Liu et al 2004b).…”

Section: Instrument and Experimentsmentioning

confidence: 97%

Seismo-Ionospheric Precursors of the 26 December 2006 M 7.0 Pingtung Earthquake Doublet

Liu¹,

Chen²,

Chen³

et al. 2008

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A network 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.