Total Electron Content Variations Observed by a DORIS Station During the 2004 Sumatra–Andaman Earthquake

International audienceFor about 40 years, ionospheric variations [including total electron content (TEC)] have been observed from time to time during large earthquakes. The TEC is the integrated electron density between a ground beacon and a satellite. It is a by-product of the International DORIS Service (IDS), which is also used for precise orbit determination of altimetric satellites. This paper reports the study of TEC variations observed by the DORIS station Cibinong, Indonesia (CICB, latitude: 6.48°S; longitude: 106.85°E) at the time of the Sumatra–Andaman earthquake (magnitude 9.2), which occurred on December 26, 2004. Numerous and intense aftershocks followed for several months after the main shock. An analysis was done to compare the variation of the TEC intensity observed by several satellites with the occurrence of these earthquakes. For comparison, the same study was also performed for another earthquake occurred very close to CICB but at a very different time. The main result is that the DORIS data show a TEC perturbation during night time close to the epicenter prior to the main Sumatra–Andaman earthquake event