Geodesy meets tectonophysics: Advancing our estimates of glacial isostatic adjustment

Abstract

Glacial isostatic adjustment (GIA) describes the response of the solid earth to ice mass changes and corresponding changes in the sea level. This process is visible in various geoscientific observations, with geodetic measurements being crucial to understand and describe the process. For example, the vertical and horizontal motion of the lithosphere is visible in GNSS (Global Navigation Satellite Systems) time series in the currently (Greenland, Antarctica, Svalbard) and formerly glaciated regions (North America, northern Europe). In addition to geodetic observations of GIA, the solid earth deformation is visible in various geological data. The vertical motion of the lithosphere can be seen in relative sea level and lake level data, but for a different epoch then GNSS data. All these observations help to explain GIA as well as infer the structure of the Earth via so-called GIA models. GIA models can be constrained by geodetic and geological observations and in turn can help to predict these observations. An essential component of GIA models is knowledge about the distribution of material parameters of the Earth’s lithosphere and mantle. This can be obtained from various geophysical measurements (e.g., gravity, seismology).Here, I will show how we can infer the depth of various material layers in the lithosphere from geodetic data exemplary for Greenland and how we can use these in three-dimensional GIA models. I will also discuss the effect of various lithosphere models on the modelled GNSS velocities.