Following the densification of GPS permanent and episodic trackers in Antarctica, geodetic observations
are playing an increasing role in geodynamics research and the study of the glacial isostatic adjustment (GIA). The
improvement in geodetic measurements accuracy suggests their use in constraining GIA models. It is essential to have a
deeper knowledge on the sensitivity of GPS data to motionsrelated to long-term ice mass changes and the present-day
mass imbalance of the ice sheets. In order to investigate the geodynamic phenomena in Northern Victoria Land (NVL),
GPS geodetic observations were made during the last decade within the VLNDEF (Victoria Land Network for
Deformation control) project. The processed data provided a picture of the motions occurring in NVL with a high level
of accuracy and depicts, for the whole period, a well defined pattern of vertical motion. The comparison between GPS-derived vertical displacementsand GIA is addressed, showing a good degree of agreement and highlighting the future
use of geodetic GPS measurements as constraints in GIA models. In spite of this agreement, the sensitivity of GPS
vertical rates to non-GIA vertical motions has to be carefully evaluated.
