Seismic reconnaissance of firn structure in Denman Glacier region, East Antarctica

The Denman Terrestrial Campaign (DTC, 2023/24) enabled investigations of firn and ice structures for various settings in a fast-changingbut little-studied region in coastal Queen Mary Land. Ice coring can inform many aspects of the firn structure; however, the spatial coverage is limited, and operational costs are high. Seismic surveying provides a noninvasive approach to recover firn depth and structure over wider areas and gain complementary insights. Three-component seismic geophones were strategically co-located with other ground-based geophysical methods and ice drill campaigns using the Rapid Access Ice Drill (RAID). We are integrating our seismic observations with these additional datasets to cross-validate our firn depth estimates and to explore the ability of seismic methods to characterise firn in future seasons. During DTC, seismic reconnaissance was carried out at sites along the edge of the continental ice sheet with distinct glacial and climate systems that affect firn-ice formation and layering. We explore an inverse ray tracing algorithm and analytical workflow that uses seismic velocities from refracted waves to provide firn depth estimates and insight into firn processes. In particular, we provide a synthetic study to show how well both methods resolve boundaries and inclusions in the firn, like ice slabs, and if we can expect to find them in the DTC seismic data. We then compare seismic velocity profiles between sites to infer if there are any differences in their firn properties and underlying physical processes.