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Katarina Vardic

Katarina Vardic

Testing the impact of Glacial Isostatic Adjustment.



Area of research

Project description

We have created a global GNSS velocity field. We use it to create plate motion models to test the impact of Glacial Isostatic Adjustment.

Glacial isostatic adjustment is the long-term response of the solid Earth to mass redistribution after the Last Glacial Maximum. It results in lateral and vertical movements of the Earth’s surface. It is difficult to distinguish from the deformational response to decadal and longer-term changes in continental water storage and the mass of glaciers and ice sheets. Thus, we must model the effects of GIA.

GIA models use an ice sheet history combined with an estimate for Earth rheology. They are tuned to fit evidence for past and present vertical motion. We determine this from relative sea-level data and GNSS-derived present-day uplift rates.

In contrast, GNSS-derived horizontal rates have not traditionally been used to tune GIA models. We know that lateral Earth structure can significantly influence horizontal rates. Most GIA models do not account for lateral structure.

Well-modelled horizontal GIA velocities are important for interpreting tectonic plate rigidity and surface mass loading. These affect the realisation of the global reference frame.

The goal of this work is to test and compare a set of GIA model predictions against a GNSS velocity field. We create a GNSS surface velocity using our in-house developed reference frame combination software TANYA. We then infer plate tectonic models and compare and test GIA models.

We will use the results to identify robust features of the GIA and residual surface velocity fields. This will reveal the response to contemporary surface mass redistribution.


Geodesy, Geophysics, GNSS, Plate tectonics, Science communication


  • MSc Geodesy and Geoinformatics
  • BSc Geodesy and Geoinformatics

twitter Katarina Vardic - @geokatarina