Acceleration of small-medium magnitude seismic activity in Greenland during 2012 to 2021

Thinning of the Greenland Ice Sheet (GrIS) induces an elastic response in the underlying crust. In recent years the thinning has accelerated resulting in larger crustal displacements at the ice sheet margin. The resulting displacement enables seismic activity. The seismic community norm is to disregard low magnitude events to remove spatial bias, and previous studies have shown no increase in seismicity around Greenland. Olivieri and Spada (2015) found that earthquakes are confined to the ice sheet margin, and the ice sheet appeared to suppress earthquakes. By use of depth distribution, they have proposed that seismicity is governed by two distinct mechanisms: Glacial Isostatic Adjustment (GIA) as the driving factor of moderate-sized crustal earthquakes regionally, whereas current ice melting drives shallow, low-magnitude seismicity. It was deemed inconclusive due to insufficient data. We included low magnitude seismicity by pulling a selection of long-term stable seismometers (8 years) on Greenland and constraining the Geological Survey of Denmark and Greenland (GEUS) Earthquake catalogue to any events measured on minimum 3 stations. While the proposed seismometer constraint enables low magnitude analysis for large regions, regional spatial bias is still a considerable factor due to the low count of long-term seismometers. Seismic events are spatially primarily confined at the ice sheet margin, whereas highest density is found within regions of high thinning and crustal displacement. Significant acceleration of small-medium magnitude seismic activity is observed from 2012 to 2021, whereas no change is observed for large magnitude seismicity. There has not been found any distinct difference in depth distribution for small-medium or large magnitude seismic events.