Absolute gravity measurements in Terre Adelie (Antarctica) and at Canberra (Australia)

Abstract

France, took absolute gravity measurements at Dumont d’Urville (Antarctica) and Canberra (Australia) in February 2006. First we report on these measurements and then we compare with previous measurements taken by the same group at Dumont d’Urville in 2000 and by American and Japanese groups at Canberra in 2003 and 2004. The results show a very large stability of the Antarctic site demonstrated both by absolute gravity variation (0 ± 1.94 $\mu Gal$/yr) and height variations from DORIS (0.29 ± 0.13 mm/yr) and GPS (- 0.01 ± 0.21 mm/yr) observations. At Canberra an uplift is observed by GPS (+ 2.39 ± 0.06 $mmyr^{-1}$) and DORIS (+ 5.49 ± 0.49 mm/yr) at the Mt Stromlo sites whereas absolute gravity would show an uplift at the seismic vault (- 2.5 ± 0.1 $\mu Gal$/yr) and a subsidence at the superconducting gravimeter site (+ 3.7 ± 1.6 $\mu Gal$/yr). At Tidbinbilla, absolute gravity variations (- 3.90 ± 0.76 $\mu Gal$/yr) and vertical GPS (+ 2.16± 0.25 mm/yr) both show an uplift. Note: in the following we shall use 1 $\mu Gal$ = 10 –8 m/s2.