Feed aggregator

SummaryShear wave splitting, caused by seismic anisotropy, provides insights into convective processes in the mantle. While upper mantle anisotropy beneath the continents is well-resolved with high lateral resolution, its characterization beneath the oceans remains limited due to the paucity of seismic stations. In this study, we leverage the sensitivity of P waves that convert to S upon reflection at the surface (PS) to infer seismic anisotropy near their bounce point. We measure PS splitting automatically from a global dataset that includes all earthquakes with magnitudes ≥5.9 from January 1995 to present, collected from 25 datacenters, totaling approximately 5,800 events and 18 million three-component seismograms. After careful quality control, we obtain 889 PS splitting measurements from this dataset, mostly for regions without other splitting constraints. These regions include the South China Sea, the Philippine Sea, the western Pacific Ocean, the western Atlantic Ocean near the Caribbean, and the South Atlantic Ocean. Where independent SKS constraints are available, these are in general agreement with our PS results. Comparisons of PS fast directions to azimuthal seismic anisotropy derived from surface waves and the direction of absolute plate motion (APM) show a dominant contribution of asthenospheric deformation to the measurements. This agreement is particularly pronounced beneath the oceans, away from subduction zones, for instance, across much of the Pacific basin. In contrast, splitting patterns near subduction zones are generally more complex: fast directions are most often trench-parallel or oblique, and only rarely trench-perpendicular, suggesting that a trench-parallel component of shear deformation is commonly generated in subduction settings, as commonly inferred from SKS splitting. We make all measurements publicly available as a data product, along with detailed metadata to enable future work.

Groundwater is a critical resource in Southern California, where long-term drought and climate change place increasing pressure on local aquifers. Some regions, like the Hollywood Basin (a small region in and around the West Hollywood neighborhood), are increasing their reliance on these aquifers in order to reduce the amount of water imported from elsewhere. A new Caltech-led study provides the most detailed picture to date of how the Hollywood Basin responds to groundwater usage, revealing that current estimates of sustainable groundwater yield may be too high.

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s):

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Rose PAQUE, Angus MOORE, Jean L. DIXON, Marcus CHRISTL, Yessenia MONTES, Veerle VANACKER

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Qian (刘倩) Liu, Joseph A. Stewart, Laura F. Robinson, Sang Chen, Maoyu Wang, Tianyu Chen, Tao Li

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): L. Guallini, R. Orosei, E. Pettinelli, G. Caprarelli

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Elizabeth W. Patterson, Alliya A. Akhtar, Michael L. Griffiths, David McGee, Quốc Đỗ-Trọng, Annabel Wolf, John A. Higgins, Stefania Gili, Mùi X. Trần, Hùng Q. Nguyễn, Trí H. Đinh, Thành N. Bùi, Kathleen R. Johnson

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): J.W.D. Strong, D.W. Davis, J. Marsh, P.C. Thurston, A.J.M. Lalonde, J.M. Simmons, K. Ross

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Claudia A. Trepmann, Lisa M. Beiers, Fabian Dellefant

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Massimo Nespoli, Maurizio Bonafede, Maria Elina Belardinelli

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Jiaxi Zhao, Yonggang Liu, Gaojun Li, Haoyue Zuo

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Yingnan Zhang, Mi Zhou, Liping Qin, Bing Yang, Haolan Tang, Thomas Smith, Huaiyu He

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Ségolène Rabin, Steven Goderis, Lisa Krämer-Ruggiu, Pim Kaskes, Jan Smit, Kasper Hobin, Frank Vanhaecke, Philippe Claeys

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Franck Poitrasson, Pierre Le Pape, Guillaume Morin, Romain Guilbaud, Camille Baya, Qianyu Deng, Jeremy Rabone, Julie Aufort, Marc Blanchard

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Axel Wittmann, Philippe Lambert

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Julia M. Ribeiro, Jian Lin, Jeff Ryan

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Naomi J. Saunders, Baptiste Debret, Jason Harvey, Edward Inglis, Alex N. Halliday

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Cuiping Wang, Haolan Tang, Bingkui Miao, Huimin Yu, Yongsheng He, Huanxin Liu, Fang Huang, Frederic Moynier, Jingao Liu

Publication date: January 2026

Source: Earth and Planetary Science Letters, Volume 674

Author(s): Yaser Noorian, Juraj Farkaš, Alan S. Collins, Robert Frei, Eva E. Stüeken, Samantha R. Walker, Claudio Delle Piane, Wei Wen Wong

Publication date: Available online 11 December 2025

Source: Advances in Space Research

Author(s): Parisa Dodangeh, Reza Shah-Hosseini, Saeid Homayouni