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Authors: Magrini, Fabrizio
Kästle, Emanuel
Pilia, Simone
Rawlinson, Nicholas
De Siena, Luca
Title: A new shear-velocity model of continental Australia based on multi-scale surface-wave tomography
Online publication date: 14-Sep-2023
Year of first publication: 2023
Language: english
Abstract: The Australian Seismological Reference Model (AuSREM) represents a state-of-the-art geophysical synthesis of the Australian continent. To date, its shear-wave component has limited resolution at lower-crustal to uppermost-mantle depths, where it is mainly constrained by sparse measurements collected at the local scale. In this study, we compile a large data set of surface-wave phase velocities based on seismic ambient noise and teleseismic earthquakes, to produce Rayleigh and Love phase-velocity maps of continental Australia in a broad period range (4–200 s). Via transdimensional Bayesian inversion, we translate the phase-velocity maps into a 3-D shear-wave velocity model extending to 300 km depth. Owing to the unprecedented seismic coverage and to the joint use of ambient-noise and teleseismic data, the retrieved model fills a tomographic gap in the known shear-wave velocity structure of the continent, comprising lower-crustal to uppermost mantle depths. Consistent with AuSREM, strong velocity heterogeneities in our model highlight the (faster) cratonic blocks and the (slower) sedimentary basins at upper-crustal depths. At mantle depths, the most prominent feature of the continent is a large-scale eastward decrease in shear-wave velocity. We interpret our observations in light of the relevant literature, and produce depth maps of the Moho and lithosphere-asthenosphere boundary (LAB). Notably, our LAB proxy features a stripe of thicker lithosphere extending to the east coast, which is not visible in the AuSREM LAB model. This observation supports the idea that lateral variations in lithospheric thickness control both the composition and volume of surface volcanism in eastern Australia.
DDC: 550 Geowissenschaften
550 Earth sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 09 Chemie, Pharmazie u. Geowissensch.
Place: Mainz
Version: Published version
Publication type: Zeitschriftenaufsatz
License: CC BY
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Journal: Journal of geophysical research : B, Solid earth
Pages or article number: e2023JB026688
Publisher: Wiley
Publisher place: Hoboken, NJ
Issue date: 2023
ISSN: 2169-9356
Publisher DOI: 10.1029/2023jb026688
Appears in collections:DFG-491381577-H

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