Controlled-source seismic imaging of the Eastern Shear Margin of Thwaites Glacier

The Thwaites Interdisciplinary Margin Evolution (TIME) project, part of the International Thwaites Glacier Collaboration (ITGC), examines the physical processes and properties at the Eastern Shear Margin of Thwaites Glacier in West Antarctica using geophysical imaging and monitoring. During 2023-24, the TIME field team collected controlled-source seismic reflection and refraction data across the Thwaites’ Eastern Shear Margin, with 1000 3-component seismic nodes deployed in a 27-km line and a 3-km by 5.5-km seismic grid. We detonated 671 seismic sources, mostly “Poulter” sources with 4-kg explosive boosters suspended on a 6-foot bamboo pole. We use these controlled-source seismic data to image the shear margin in two and three dimensions, including englacial, bed, and sub-ice geologic imaging and interpretation. Seismic sources were recorded with high signal to noise ratios across the full extent of the seismic line and grid and penetrated into the bed beneath the ice (~2000-km-thick). We present two- and three-dimensional seismic reflection images of the shear margin environment as well as seismic refraction velocity models. We compare the seismic images and seismic refraction velocity models to co-located airborne radar data. The seismic images, seismic velocity models, and radar data shed new light on physical properties of the ice and bed across the shear margin.