Abstract

Seismic waves, generated both within the ice and by distant earthquakes, provide a unique window into some of the most inaccessible environments on Earth. In this way, cryoseismology, a rapidly evolving branch of seismology, offers a wide and exciting range of opportunities to study the glacial and subglacial environments of polar and mountain regions. Such observations are invaluable to our understanding of the cryosphere and for constraining how ice sheets will respond to a warming world. In this talk, I will present results from two studies that demonstrate how cryoseismology can be used to improve our understandings of the Antarctic Ice Sheet. Starting small, an array of accelerometers and geophones deployed on the Larsen C Ice Shelf in 2022 detected 108 icequakes originating from within the ice shelf. Correlations between icequake explosivity and tidal phase suggest that this micro-seismicity is predominantly driven by tidal infiltration and circulation of seawater in the ice. In combination with radar data, this novel observation provides new insight into how rifting, which eventually leads to the calving of large tabular icebergs such as A68 , can be controlled by the internal structure of ice shelves, with important implications for their long-term stability. At the other end of the scale, the growing number of seismic deployments across Antarctica has enabled the use of teleseismic earthquakes to investigate the continent’s lithospheric structure. These data, however, also record information about the basal conditions of the Antarctic Ice Sheet. By building on established receiver function and P-wave coda autocorrelation methods, both the extent of subglacial sediment and the presence of subglacial till can be constrained. Rutford Ice Stream provides an ideal natural laboratory for testing this approach, with complementary radar, active-source seismic, and drilling data allowing the seismic signatures of subglacial till to be robustly validated. This proof of concept is then extended across Antarctica, where mapping the distribution of this deformable till can inform ice sheet models and reduce uncertainties in the consequent sea-level rise predictions.