East Antarctic tectonic basin structure and its implications for ice-sheet modeling and sea-level projections

The volume of the East Antarctica Ice Sheet is equivalent to ~52 m of sea-level rise, but whether the ice sheet is a major contributor to global sea-level increase remains debated. How an ice sheet responds to climate-induced perturbations strongly depends on the physical conditions below the ice-bed interface; therefore, constraining the solid Earth structure beneath East Antarctica is critical. However, sparse seismic station coverage has limited our ability to image key characteristics. Here we employ full-waveform ambient noise tomography, an approach that better resolves Earth structure in sparsely sampled areas compared to traditional techniques, and our results reveal previously unrecognized, low-velocity anomalies under the Wilkes and Aurora Subglacial Basins. Our findings suggest thinner-than-expected lithosphere and thermally perturbed upper mantle, implying drastically different geothermal heat flux and mantle viscosity inputs compared to those from prior tomographic studies. This has notable implications for accurate ice-sheet modeling and future global sea-level projections. Low-velocity anomalies suggest thin lithosphere and thermally perturbed upper mantle under the Wilkes and Aurora Subglacial Basins in East Antarctica, according to full-waveform ambient noise tomography analysis.