The absolute gravimeter is used, in conjuction with the NASA GPS receiver, to monitor vertical crustal motion and changes in gravity. The goal is to detect the deformation of Earth caused by changes in the ice load. There is an elastic response of Earth to on-going changes in the ice, and a viscous response caused by any changes in the ice load that have occured over the last few thousand years. By combining GPS vertical uplift and the measured changes in absolute gravity, it's possible to separate the two effects. This is a campaign instrument, deployed at the site almost every summer beginning in 1995.


Tonie van Dam
European Center of Geodynamics and Seismology