Recent Ground Displacement Over Permafrost in Midwestern Spitsbergen, Svalbard: InSAR Measurements and Modeling

Quantifying the characteristics of ground displacement is of great importance for understanding the geological, hydrological, and biochemical processes occurring due to widespread permafrost degradation. This study investigated the dynamics of annual and seasonal ground displacement over permafrost in midwestern Spitsbergen, Svalbard, using radar interferometry (InSAR) and a permafrost thermal model. Permafrost ground displacement exhibited an evident and widespread subsidence at a rate of similar to 2.0 mm/yr during 2018-2021. A composite thermal index model was applied to simulate thawing-season ground displacement in four in situ boreholes based on the in situ observations and the ERA5 Land reanalysis temperature, respectively. The modeled seasonal ground subsidence demonstrated a similar pattern with InSAR measurement (correlation coefficient: 0.86-0.91), indicating the practicability of employing reanalysis temperature in large-scale ground subsidence modeling over data-sparse permafrost regions. The effects of environmental driving factors, including temperature and landcover, on ground displacement were also discussed. This study confirmed the availability of integrating InSAR measurement and thermal-modeled results toward a comprehensive understanding of ground displacement over permafrost regions.