Waveform Tomography of the Antarctic Plate

• Main Authors: Chua, Ee Liang, Lebedev, Sergei
• Format: Conference Object
• Language: English
• Subjects: Antarctic; Byrd; Coats Land; East Antarctica; Marie Byrd Land; The Antarctic; Transantarctic Mountains; Victoria Land; West Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: https://dair.dias.ie/id/eprint/1414/; https://dair.dias.ie/id/eprint/1414/1/EL_AGU23_poster_FINAL_smalldigital.pdf

The Antarctic plate consists of a continent, characterized by a complex assemblage of geological units, encompassed by oceanic lithosphere and predominantly surrounded by mid-oceanic ridges. The continent’s highly heterogenous lithosphere, extensive ice sheet coverage and other contributing factors render it one of the least well-studied regions of the Earth’s interior. The past two decades have seen a significant rise in the number of seasonal deployments and new permanent stations, augmenting the still sparse station coverage in Antarctica. To achieve the most comprehensive sampling of the Antarctic Plate's crust and upper mantle, we assembled a dataset comprising all publicly available broadband seismic data. The dataset is refined by selecting event-station pairs with paths that sample the Southern Hemisphere, followed by rigorous automatic and manual quality control procedures. This yielded a very large dataset of almost 0.8 million vertical-component seismograms. The new S-wave velocity tomographic model of the Antarctic plate is computed using the Automated Multimode Inversion (AMI) scheme. The AMI method initially derives structural details from surface, S-, and multiple S-waves as sets of linearly independent equations. Subsequently, these equations are merged into a singular large linear system, which is solved to produce a tomographic model of the Antarctic crust and upper mantle. We observe the clear delineation of East and West Antarctica by a strong velocity gradient that bisects the continent extending from Coats Land to Victoria Land, following the Transantarctic Mountains. West Antarctica and its offshore are observed to be underlain by low S-wave velocity anomalies that connect Marie Byrd Land with the Amundsen, Bellingshausen and Ross seas. The highest S-wave velocity anomalies are observed in East Antarctica, most of which is underlain by thick, cold cratonic lithosphere. The model maps the boundaries of the cratonic lithosphere and, also, the substantial intra-cratonic heterogeneity present. ...