Joint Study Group

JSG 3.1: Geodetic, Seismic and Geodynamic Constraints on Glacial Isostatic Adjustment (joint with IASPEI and IAG Commissions 1 and 2)

Chair: Rebekka Steffen (Lantmäteriet, Gävle, Sweden)

Vice-Chair: Erik R. Ivins (Jet Propulsion Lab., California Institute of Technology, Pasadena, USA)


  • to review the integration of geophysical, seismological, and geodynamical modelling as well as fundamental mineral physics into GIA models, with a special emphasizes on their model results (including gravity changes and GNSS rates);
  • to formulate general principles for defining the lithosphere for GIA models and assessment of the rheological principles and geophysical observables relevant to that definition;
  • to study the relative merits of GIA data types. These data types include GNSS horizontal and vertical motion, tide gauges, gravity changes, observed with both terrestrial and space, techniques, and seismicity, in form of paleo, historic and recent earthquakes. These data are especially powerful when combined with one another. Special emphasis should be placed on evaluating the spatial distribution of data and the length of time series required for GIA modelling;
  • to assess the role of GIA model impact on products derived from modern space gravimetry (GRACE) for both ocean and hydrological sciences;
  • to intercompare model based transient response of post-seismic relaxation following 
  • Mw > 7.0 earthquakes to the constitutive laws assumed valid in GIA models;

IAG Events