Seismic full-wavefield imaging of the West Antarctic Ice Sheet interior near the ice flow divide

• Published in: Earth and Planetary Science Letters
• Main Authors: Zhang, Zhendong, Nakata, Nori, Karplus, Marianne, Kaip, Galen, Qin, Lei, Li, Zhengbo, Shi, Caiwang, Chen, Xiaofei
• Other Authors: Key Laboratory of Deep Petroleum Intelligent Exploration and Development, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, 02139, MA, USA, Energy Geosciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, CA, USA, Department of Earth, Environmental and Resource Sciences, University of Texas at El Paso, El Paso, 79968, TX, USA, School of Geophysics and Geomatics, China University of Geosciences, Hubei, 430074, China, Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier BV 2024
• Subjects: Antarc*; Antarctic; Ice Sheet; Thwaites Glacier
• Online Access: http://hdl.handle.net/10754/698108; https://doi.org/10.1016/j.epsl.2024.118701

The properties and behavior of the West Antarctic Ice Sheet through time are key to understanding climate and sea level change in the near future. We analyze different types of seismic waves from an active-source acquisition deployed on the West Antarctic Ice Sheet and uncover the internal structures of the ice sheet using seismic imaging methods. Surface waves including leaky and normal modes are separated from englacial and bed reflections using a cross-component matched filter method. Leaky modes are uniquely strong in the data possibly due to the firn layer and ice compaction. We use a joint inversion of leaky and normal surface waves for P- and S-wave velocity estimation in the near-surface and attribute the ultra-low Vp and Vs ratios to the pore closure. We observe englacial reflections down to 50 Hz and bed reflections with multiple branches. Such reflection waves are further used to calculate the seismic images of discontinuities in the ice sheet and the bedrock, revealing multiple layers within the ice near the bed and a heterogeneous bedrock with a rugged surface and possibly existing faults. The fine structure of the ice sheet revealed by seismic data helps with searching for possible drain points and evaluating the instability of the ice sheet. Our data analysis shown in the study is also applicable to typical data sets collected for critical zone exploration. We thank the High Performance Computing (HPC) team at King Abdullah University of Science and Technology (KAUST) for providing guidance on using IBEX and Shaheen clusters. The computing for this project was partly performed at the University of Oklahoma (OU) Supercomputing Center for Education & Research (OSCER). This work is from the Thwaites Interdisciplinary Margin Evolution (TIME) project, a component of the International Thwaites Glacier Collaboration (ITGC). Support from National Science Foundation (NSF: OPP-1739027) and Natural Environment Research Council (NERC: Grant NE/S006788/1). Logistics provided by NSF-U.S. Antarctic Program ...