Research findings by a group led by Professor Yuji Yamamoto of Marine Core Research Institute（MaCRI） have been published in the academic journal *Geophysical Research Letters*
Release Date:
Evidence That an “Undiscovered Reversal” Lurks in the History of Geomagnetic Reversals — Visualizing the Need for High-Resolution Surveys Through Statistical Analysis —
Marine Core Research Institute（MaCRI）Professor Yuji Yamamoto of the National Institute of Polar Research, along with Yutaka Yoshimura, a Specially Appointed Researcher at the National Institute of Polar Research (at the time of the research),Yutaka Yoshimura, a Specially Appointed Researcher at the National Institute of Polar Research (at the time of the research), Masakazu Fujii, Assistant Professor at the National Institute of Polar Research/Comprehensive Research Graduate School, Professor Hideichi Hino, Specially Appointed Professors Shotaro Ako and Tetsu Kuriki of the Institute of Statistical Mathematics/Comprehensive Research Graduate School, and others, discovered evidence suggesting the existence of “undiscovered reversals” by conducting a statistical analysis of the history of geomagnetic reversals over the past 155 million years.These findings suggest the need for high-resolution paleomagnetic observations on the seafloor and at terrestrial outcrops from periods where “undiscovered reversals” may be hidden.
Going forward, this research is expected to enhance our understanding of the long-term behavior of the Earth’s magnetic field and improve the accuracy of reconstructing the history of changes within the Earth.
The findings of this study were published on February 23 in the academic journal *Geophysical Research Letters*.
The detailed geomagnetic reversal frequency model reconstructed in this study is shown in black. The black-and-white bands represent the geomagnetic polarity chronology (Ogg, 2020; plotted using data from the Geologic Time Scale 2020, Elsevier).The map of the Earth’s seafloor structure shows, in colored areas, the seafloor ages where “undiscovered geomagnetic reversals” are thought to lie (map created using data from Müller et al., 2019, Tectonics).
Published in: Geophysical Research Letters
Title: Evidence for Missing Geomagnetic Reversals from a Geomagnetic Reversal Frequency Model Using Adaptive Kernel Density Estimation
Author: Yutaka Yoshimura (Project Researcher, Geosphere Research Group, Division of Advanced Research Promotion, National Institute of Polar Research (at the time of the research); Doctoral Candidate, Institute of Atmospheric and Oceanic Research, The University of Tokyo (at the time of the research). Currently, Special Researcher (JSPS) at the Institute for Comparative Social and Cultural Studies, Kyushu University Graduate School)
Masakazu Fujii (Assistant Professor, Geosphere Research Group, Division of Advanced Research Promotion, National Institute of Polar Research / Assistant Professor, Graduate School)
Hideyuki Hino (Professor, Institute of Statistical Mathematics / Professor, University of Graduate School)
Shotaro Ako (Specially Appointed Professor, Institute of Statistical Mathematics / Visiting Professor, Graduate School)
Tetsu Kuriki (Specially Appointed Professor, Institute of Statistical Mathematics / Visiting Professor, Graduate School)
Osamu Ishizuka (Principal Researcher, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology; Visiting Researcher, Japan Agency for Marine-Earth Science and Technology)
Toshitsugu Yamazaki (Professor, Institute of Atmospheric and Oceanic Research, University of Tokyo [at the time of the research]; Professor Emeritus, University of Tokyo; Visiting Professor, Kochi University)
Hyeon-Seon Ahn (Korea Institute of Geoscience and Mineral Resources, Senior Researcher; KIGAM School, University of Science and Technology, Associate Professor (adjunct))
Tesfaye Kidane (Wayne State University, Professor)
Yuji Yamamoto (Professor, Kochi University; Marine Core Research Institute（MaCRI） )
Yoichiro Otofu (Professor Emeritus, Kobe University / Director, Institute for the History of the Earth)
URL: https://doi.org/10.1029/2025GL120557
DOI: 10.1029/2025GL120557
Paper Publication Date: February 23, 2026, at 11:00 p.m. (Japan Standard Time)
This research was supported by the Comprehensive Research Program “ Graduate School” University Data Scientist Researcher Training System Project, JSPS Grants-in-Aid for Scientific Research (JP22K14124, JP25KJ0258, JP25K01103, JP23K22608,JP23K24909, JP25K15034), the KIGAM Basic Research Project (25-3111-3), the Research Institute of Information and Systems Strategic Research Project (2024-SRP-02), and the Earthquake Research Institute, The University of Tokyo Joint Research Program (2024-B-01).