Abstract
The NZGD2000 is the official 3-D semi-dynamic geodetic datum for New Zealand that incorporates a deformation model to correct the horizontal coordinates and survey observations for the effect of regional-scale tectonic movements of the Earth's crust. These horizontal tectonic deformations are up to a few centimetres per year. Except for the Southern Alps (central South Island) and the Taupo volcanic zone (North Island), the currently available information indicates that the vertical tectonic deformations are an order of magnitude smaller than the horizontal components. In this study we compile a preliminary map of vertical deformations in New Zealand using the GPS time series. The least-squares linear regression analysis is used to estimate the vertical velocities at GPS sites. After applying outlier detection, the vertical deformations are investigated with respect to the tectonic setup of New Zealand. The results reveal that the uplift of the Southern Alps at the currently established GPS sites reaches 6 mm/year. The largest regional-scale tectonic subsidence, at approximately 9 mm/year, is detected in the lower and central part of the North Island. The estimated vertical tectonic deformations are compared with evidence from geochronological data and results of previous studies.