https://youtu.be/CaY_3YA7dgA

This paper explores the use of full-waveform inversion (FWI) to analyze Earth's mantle structure, revealing a more complex and heterogeneous picture than previously seen with traditional travel-time tomography. The study highlights numerous previously undetected positive wave speed anomalies in the mid- and lower mantle, many of which are located below major oceans and continental interiors with no record of subduction. These findings challenge the long-held assumption that most lower mantle positive wave speed anomalies represent cold, subducted slabs. The research indicates that these anomalies may have diverse origins, including delaminated lithosphere, compositional variations, and other thermal and chemical heterogeneities. The authors emphasize that the spatial bias of travel-time tomography may have led to the previously assumed correlation between positive anomalies and subduction zones. The study also demonstrates that FWI is more sensitive to mantle structure, particularly in regions with limited seismic sources and receivers, and is less dependent on source-receiver geometry than travel-time tomography. The results suggest that a one-to-one correspondence between positive wave speed anomalies and subducted slabs is unlikely. Statistical analysis in this paper shows no significant correlation between positive wave speed anomalies and reconstructed locations of former subduction zones when using FWI data. These findings underscore the potential of FWI for future mantle exploration and highlight the need to reconsider the interpretation of mantle structures and the dynamics of convection. P. Geo. Ricardo A Valls, M. Sc. and Geo Gadfly Valls Geoconsultant ORCID ID- https://orcid.org/0000-0002-5421-0914 Scopus Author ID: 7003369619/35335510700 ResearcherID: S-6604-2018 If you like this content, please "buy me a coffee" https://www.buymeacoffee.com/goldendroplets