Ground deformation and gravity variations modelled from present-day ice thinning in the vicinity of glaciers

• Published in: Journal of Geodynamics
• Main Authors: Memin, Anthony, Rogister, Y., Hinderer, J., Llubes, M., Berthier, E., Boy, J.-P.
• Other Authors: Institut de physique du globe de Strasbourg (IPGS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: ground tilt; gravity variations; elastic deformations; present-day ice thinning; [SDU]Sciences of the Universe [physics]; Svalbard; Norway; Mont Blanc
• Online Access: https://hal.science/hal-00594427; https://hal.science/hal-00594427/document; https://hal.science/hal-00594427/file/PEER_stage2_10.1016%252Fj.jog.2009.09.006.pdf; https://doi.org/10.1016/j.jog.2009.09.006

International audience The solid Earth deforms because of post-glacial rebound due to the viscous relaxation following the last deglaciation but also because of present-day elastic deformation induced by ice thinning. In this paper, we compute elastic loading Green's function associated to the tilt of the ground in the vicinity of glaciers using a Love number formalism for a stratified non-rotating spherical Earth model. We compare this global approach with the plane approximation in terms of height, gravity and tilt changes as a function of the distance from the measurement point to the load. We find that Green's functions for the vertical displacement (resp. horizontal displacement, elastic part of the tilt) agree to within 1% up to ∼400 m (resp. 2km, 5km) from the glaciers.Two specific cases of ice thinning are considered:1/ the alpine glaciers of the Mont Blanc region (France) where ice-thickness variations are derived from differential digital elevation model analysis for the period 1979-2003; 2/ the Svalbard (Norway) glaciers by considering the ice model SVAL. We show that the rates of ground tilt are well above the limit of detection of up-todate long base hydrostatic tiltmeters, which, if installed next to the glaciers, could be used to monitor the time evolution of ice thinning. We also show that the topography has a strong influence on the gravity variations near the glaciers.