Quantifying the Impact of Modern Ice Mass Loss on Crustal Strain and Seismicity across Greenland and the European Arctic

Ice mass loss from the Greenland Ice Sheet and Arctic glaciers has accelerated over the last three decades due to rapid changes in Arctic climate. This loss of ice from glaciated areas and redistribution of water across the global oceans creates a complex spatio-temporal pattern of crustal deformation due to the load changes on Earth’s surface. We test whether the resulting strain perturbations from this deformation are large enough to influence seismic activity in the Arctic on decade to century timescales.

 

Using new ice-mass-loss estimates from radar altimetry for the Greenland Ice Sheet and model reconstructions of glaciers across the European Arctic, we predict gravitationally self-consistent sea level changes across the Arctic over the last three decades. These surface loads are then used as input for our deformation model, developed to calculate strain at depth within the crust, using a Love number formulation for a spherically symmetric Earth. Our global model captures both the near-field effects directly beneath ice centers and deformation across the sea floor, allowing us to fully quantify the spatio-temporal perturbations to the regional strain field created by glacial isostatic adjustment (GIA) processes. Using declustered earthquake catalogs of Arctic earthquake activity over the last three decades, we search for correlation between the earthquake record and our modelled strain perturbations. In particular, we focus our search along the Mid Atlantic Ridge and beneath Greenland. In the former, small magnitude GIA-related strains enhance or counteract rapid tectonic background loading, while in the latter intra-plate setting, GIA processes likely dominate the crustal strain field.

 

While correlations over the last three decades may not be statistically definitive, this framework also allows for prediction of crustal strain patterns for future ice sheet scenarios, as ice mass loss from Greenland accelerates, and therefore predictions of the likelihood and potential geographic variability of climate-change-induced seismicity in the future.