Seismic detection of ridging and ice deformation in coastal sea ice near Utqiagvik, Alaska

Abstract:

As climate change hits the Arctic hardest, coastal sea ice is forming later in the winter and seems to be less stable throughout the season. Shore-fast sea ice – coastal sea ice that is frozen to shore and stabilized by ice ridges extending down to the sea floor – protects the shoreline from erosion by large winter storms and provides a stable platform for travel and subsistence hunting activities in local communities. In order to form shore-fast ice, coastal ice develops deep ridges through repeated collisions with the drifting pack ice. This project examines seismic data from a nearby station in Utqiagvik, Alaska and shows that these ridge-building events can be detected at up to several kilometers from shore. Ridging events have a unique spectral signature and can be distinguished from breakout events (where unstable shore ice cracks and drifts away from shore), wind-related signals, and anthropogenic noise. This suggests that a network of seismic stations across the Arctic coastline could monitor shore-fast ice development where other methods are not available.