HR: 0800h
AN: S31A-0209    [Abstracts]
TI: Seismic source characterization by ionospheric sounding from Gound Positioning System data
AU: * Rolland, L
EM: rolland@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, av. de Neptune, Saint-Maur, 94107, France
AU: Lognonné, P
EM: lognonne@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, av. de Neptune, Saint-Maur, 94107, France
AU: Kherani, A E
EM: alam@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, av. de Neptune, Saint-Maur, 94107, France
AU: Crespon, F
EM: francois.crespon@noveltis.fr
AF: NOVELTIS, 2, Avenue de l'Europe, Ramonville, 31520, France
AU: Murakami, M
EM: mccopy@gsi.go.jp
AF: Geographical Survey Institute of Japan, Geography and Crustal Dynamics Research Center, Kitasato-1, Tsukuba, 305-0811, Japan
AB: Imaging the terrestrial ionosphere is becoming possible since the installation of dense GPS networks, with a temporal and spatial resolution allowing the detection of ionospheric seismic waves. Since the 1960s, ionospheric seismic waves are detectable almost punctually after large shallow earthquakes, with current minimum magnitude of 6.5. Most recently, the use of dense networks gave the way to a global visualization of the horizontal propagation of co-seismic ionospheric disturbances. Such a use of a Global Positioning System array, and the sounding capability of the method above the ocean, prove the potential of this method as a complement to more traditional techniques used in seismology. From now on, after imaging seismic waves in the ionosphere, the challenge is the characterization of the seismic source, whose rupture involves coupling mechanisms between the moving solid earth and its surrounding atmosphere. The study presented here is based on the Total Electronic Content variations mapped close to the source and shortly after the Tokachi-Oki earthquake (M=8.3) that occurred on September, 25, 2003, in Japan. The first fundamental source parameters derived from 1 Hz sampled data will be reminded here. The rupture process is then pre-modelled in reference to the co-seismic displacements estimated by other techniques. Therefore, a modelling of the horizontal propagation of acoustic waves generated by three aligned separated sources is developed. The preliminary results of the subsequent GPS data inversion tests will be presented. Finally, for physical modelling of the vertical propagation, we used ray tracing in the atmosphere, in order to study the effects of the near-field pulse spreading in acoustic domain as well as the redistribution of the charged particles under geomagnetic dependency.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2487 Wave propagation (0689, 3285, 4275, 4455, 6934)
DE: 7215 Earthquake source observations (1240)
SC: Seismology [S]
MN: 2007 Fall Meeting