Seismic data analysis for subglacial lake D2 beneath David Glacier, Antarctica

Abstract. Subglacial lakes beneath Antarctic glaciers are pivotal in advancing our understanding of cryosphere dynamics, basal hydrology, and microbial ecosystems. We investigate the internal structure and physical properties of Subglacial Lake D2 (SLD2), located beneath David Glacier in East Antarctica, using seismic data acquired during the 2021/22 austral summer. The dataset underwent a comprehensive processing workflow, including noise attenuation, velocity analysis, and pre-stack time migration. Migrated seismic sections revealed distinct reverse- and normal-polarity reflections at the glacier–lake and lake–bed interfaces, respectively. We compared the synthetic seismogram generated through wave propagation modelling based on our structural interpretation of the migrated sections with the field data to validate the subglacial lake structure inferred from the seismic data. This confirmed a water column thickness ranging from around 53 to 82 m and delineated the broader structure of the subglacial lake. Also, discontinuous reflections detected on seismic sections transverse to the ice flow were interpreted as scour surfaces formed by ice movement. Comparison with airborne ice-penetrating radar (IPR) data acquired in 2018 further supported the consistency of the ice thickness estimates. Notably, a steeply dipping bedrock boundary identified along profile 21YY provided a more precise definition of the lateral extent of SLD2 than was possible using IPR data alone. Collectively, these findings enhance our understanding of subglacial lake environments and inform the selection of future drilling sites for in situ sampling.