Wednesday 24 August 2005

G3 1330-1600 hours

285
Absolute gravity measurements in the southern Indian Ocean
Amalvict, Martine^1,2, Rogister, Yves¹, Luck, Bernard¹, Hinderer, Jacques¹
1 IPGS./EOST (UMR CNRS/ULP 7516), Strasbourg cedex, France
2 NIPR, Tokyo, Japan
Author email: mamalvict@eost.u-strasbg.fr
In March - April 2005, Absolute Gravity (AG) has been measured by the Strasbourg gravimetry team using gravimeter FG5#206 at 4 French Scientific stations in the Indian Ocean. Crozet, Kerguelen and Amsterdam are isolated Islands situated approximately 3000 km to the South of La Réunion. Four times a year, the multi-purpose ship Marion Dufresne II connects them to La Réunion. Measurements were taken at Crozet from 8 to 10 March, at Kerguelen from 14 to 18 March, at Amsterdam from 20 to 24 March. Moreover AG was measured at the Volcanic Observatory of Piton de la Fournaise, Réunion Island, from 31 March to 4 April. The 2005 AG measurements were the first ever done at Amsterdam Island. On the contrary, AG measurements were previously operated at Crozet in 2003, Kerguelen in 2001 and 2003, and finally at Réunion Island in 2001 and 2003. Here, we report on the first AG measurement at Amsterdam, present the 2005 AG values at each station and compare them to previous ones. We pay special attention to the comparison of the gravity changes with available vertical velocities derived from precise positioning techniques (GPS, DORIS) or prediction models.

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