HR: 11:35h
AN: SF52A-06    [Abstracts]
TI: 3D Tomography of Ionospheric Perturbations Produced by Earthquakes Using Global Positioning System
AU: * Crespon, F
EM: crespon@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, D\'epartement de G\'eophysique Spatiale et Plan\'etaire, 4 avenue de Neptune, St Maur des Foss\'es, 94107 France
AU: Garcia, R
EM: garcia@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, D\'epartement de G\'eophysique Spatiale et Plan\'etaire, 4 avenue de Neptune, St Maur des Foss\'es, 94107 France
AU: Lognonn\'e, P
EM: lognonne@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, D\'epartement de G\'eophysique Spatiale et Plan\'etaire, 4 avenue de Neptune, St Maur des Foss\'es, 94107 France
AU: Murakami, M
EM: mccopy@gsi.go.jp
AF: Geographical Survey Institute, Geography and Crustal Dynamics Research Center, Kitasato-1, Tsukuba, 305-0811 Japan
AB: The recent development of Global Positioning System led to establish dense regional networks of bistatic GPS receivers providing today a powerful ionospheric observing system. Now the ionosphere can be imaged by tomographic methods using GPS data. Therefore the ionospheric perturbations can be characterized by monitoring Total Electronic Content (TEC). These disturbances have multiple sources located adove and below ionospheric layers. The most known are the Travelling Ionospheric Disturbances (TID) produced by internal gravity waves. But some ionospheric disturbances are also due to infrasonic waves. We focus this study on ionospheric perturbations generated by infrasonic waves exited by seismic waves, resulting from the coupling between Earth and the atmosphere. We present a spectral analysis of TEC GPS data, the 3D tomographic method and its application to post-seismic perturbations. By removing background noise we are able to monitor acoustic post-seismic waves, generated by the rupture process and the seismic surface waves, that reach the ionosphere. Especially, we show the observations for the Denali earthquake of $3^{rd}$ November 2002 and the Hokkaido earthquake of $25^{th}$ September 2003 using respectively the Californian networks (SICGN) and the Japan network (GEONET). Both the horizontal and vertical propagation of the waves are vizualized in the 3D tomographic movies. The observed waves arrive with a timing and a propagation velocity coherent with expected waves and we purpose an interpretation in terms of infrasonic waves in the atmosphere, generated both near the epicenter and at further distance, at the level of the Rayleigh waves front. Finally we present the improvement of the 3D tomographic methods with the advent of the Galileo system and possible application in seismology.
DE: 2435 Ionospheric disturbances
DE: 2494 Instruments and techniques
SC: Special Focus: Advances in Data Acquisition, Management, Analysis and Display [SF]
MN: 2004 AGU Fall Meeting