Fichtner, AndreasKennett, Brian L. N.Tsai, Victor C.Thurber, Clifford H.Rodgers, Arthur J.Tape, CarlRawlinson, NicholasBorcherdt, Roger D.Lebedev, SergeiPriestley, KeithMorency, ChristinaBozda, EbruTromp, JeroenRitsema, JeroenRomanowicz, BarbaraLiu, QinyaGolos, EvaLin, Fan-Chi2025-05-302025-05-300037-1106WOS:001262727800001http://www.scopus.com/inward/record.url?scp=85195451620&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733755393Seismic tomography is the most abundant source of information about the internal structure of the Earth at scales ranging from a few meters to thousands of kilometers. It constrains the properties of active volcanoes, earthquake fault zones, deep reservoirs and storage sites, glaciers and ice sheets, or the entire globe. It contributes to outstanding societal problems related to natural hazards, resource exploration, underground storage, and many more. The recent advances in seismic tomography are being translated to nondestructive testing, medical ultrasound, and helioseismology. Nearly 50 yr after its first successful applications, this article offers a snapshot of modern seismic tomography. Focused on major challenges and particularly promising research directions, it is intended to guide both Earth science professionals and early -career scientists. The individual contributions by the coauthors provide diverse perspectives on topics that may at first seem disconnected but are closely tied together by a few coherent threads: multiparameter inversion for properties related to dynamic processes, data quality, and geographic coverage, uncertainty quantification that is useful for geologic interpretation, new formulations of tomographic inverse problems that address concrete geologic questions more directly, and the presentation and quantitative comparison of tomographic models. It remains to be seen which of these problems will be considered solved, solved to some extent, or practically unsolvable over the next decade.The authors gratefully acknowledge invaluable support provided by the Seismological Society of America, and, in particular, by Nan Broadbent and Rikki Anderson, during the organization of the 2022 Seismic Tomography conference in Toronto. Countless discussions and interesting presentations made the meeting a real success. Contribution of A. R. and C. M. prepared by LLNL under Contract Number DE-AC52-07NA27344. E. B. acknowledges the support by the National Science Foundation (NSF) under Award Number EAR1945565 and the Texas Advanced Computing Center (TACC) at the University of Texas at Austin for providing computational resources on the Frontera system (Stanzione et al. , 2020) through allocation EAR21003 (www.tacc.utexas.edu, last accessed April 2024) . S. L. acknowledges support from the Natural Environment Research Council (NERC) , UK, under Grant Number XE/X000060/1. V. C. T. acknowledges support from National Science Foundation (NSF) Grant Number EAR-2011079. C. T. was supported by National Science Foundation Grant Number EAR 2342129.29enPublisher Copyright: © Seismological Society of America.Wave-form inversionSpectral element methodAmbient noise tomographyShear velocity structureFrequency travel-timesUpper-mantle structureSurface-waveP-waveThermal structureElastic-waves202410.1785/012023022985195451620