Strain rate computation in Northern Victoria Land (Antarctica) from episodic GPS surveys

The monitoring of crustal motions in Northern Victoria Land (NVL) of Antarctica by means of episodic GPS stations (EGPSs) provides an accurate and dense (∼50-km spaced) velocity field. The data, gathered starting in Austral summer 1999, derive from a series of benchmarks belonging to the Victoria Land Network for DEFormation control (VLNDEF) geodetic network. The velocity uncertainties are checked on the basis of length and returning time of the episodic surveys, to obtain a meaningful strain rate field by means of a least-square computation where the contribution of a GPS station is weighted by the inverse square of its velocity error. The study shows that the NVL is characterized by a complex kinematics and that, although three subregions with different prevailing deformational behaviour can be recognized, the single blocks cannot be resolved because too few stations exist. Only features having 150–200 km size at least can be recognized. Moreover, it is demonstrated that an appropriate data processing of EGPS data can lead to an accurate evaluation of the strain rate field even in a harsh environment like Antarctica.