observation of vertical electron density profile in inospheric elayer during indianocean earthquake on december 2004 using champ satellite

This paper describes the observation and analysis of vertical electron density before major earthquake above the sumatramalaysia region during indian ocean major earthquake in 2004 in aceh, sumatra. the electron density profile in elayer of ionosphere a few days before earthquake and a few hours after earthquake have been observed using the data from the champ satellite. the data obtained from the champ satellite based on gps radio occultation technique, starting from 21st dec, 2004 until 27th dec, 2004, between 90 120 km altitude ranges. it is shown that significant anomaly can be detected as early as 3 days before the major earthquake above the preparation zone of earthquake epicentre through significant disturbances of the electron concentration in the ionosphere. in addition, the electron density in the ionosphere above the earthquake epicentre is observed to be very high during 8 hours before earthquake occurred. after a day of the earthquake occurrence, it is observed that the electron density decreases and the ionospheric region become more stable.