Seismo-ionospheric precursor of the 2008 Mw7.9 Wenchuan earthquake observed by FORMOSAT-3/COSMIC

Chun Chieh Hsiao, J. Y. Liu, K. I. Oyama, N. L. Yen, Y. A. Liou, S. S. Chen, J. J. Miau

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The seismo-ionospheric precursor prior to the Mw7. 9 earthquake near Wenchuan, China, on 12 May 2008 was observed by the FORMOSAT-3/COSMIC satellite constellation. By binning radio occultation observations, the three-dimensional ionospheric structure can be obtained to monitor the ionospheric electron density variation prior to the earthquake. It has been determined that near the epicenter the F2-peak height, hmF2, descends about 25 km and the F2-peak electron density, NmF2, decreases about 2 × 105 el/cm3 around noon within 5 days prior to the earthquake. The integrated electron content decreases more than 2 TECU between 250 and 300 km altitude.

Original languageEnglish
Pages (from-to)83-89
Number of pages7
JournalGPS Solutions
Issue number1
StatePublished - Jan 2010


  • Earthquake
  • GPS
  • Ionosphere
  • Radio occultation
  • Satellite


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