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Key role of clays in the 2011 Tohoku mega-earthquake
An international research team from the IODP program has uncovered new insights into the exceptional behavior of the 2011 Tohoku earthquake (Mw 9.1), which struck northeastern Japan and generated a massive tsunami, devastating coastal communities and notably the Fukushima Daiichi nuclear power plant.
Rock cores from boreholes C0019J and C0019K drilled during IODP Expedition 405, containing the fault zone that ruptured during the Tohoku earthquake.
The study, published on 18 December 2025 in the journal Science, is based on the results of the IODP Expedition 405 JTRACK and on the collection of samples and geophysical data in the subduction zone offshore the Japan Trench. The authors include researchers from GeoRessources (Marianne Conin, co–chief scientist of the expedition), ISTerre (Mai-Linh Doan and Pei Pei), Ifremer / ISMER (Morgane Brunet), and Géosciences Montpellier (Erwan Le Ber).
The results also show that lithostratigraphy controls fault localization and that in situ observations are essential to identify zones of concentrated slip and to assess the tsunamigenic potential of subduction zones. This work contributes to a more accurate assessment of seismic and tsunami hazards for coastal communities worldwide.
The publication coincides with the release of a documentary dedicated to the expedition, and additional data from the expedition will soon be made publicly available by the IODP.
The results also show that lithostratigraphy controls fault localization and that in situ observations are essential to identify zones of concentrated slip and to assess the tsunamigenic potential of subduction zones. This work contributes to a more accurate assessment of seismic and tsunami hazards for coastal communities worldwide.
The publication coincides with the release of a documentary dedicated to the expedition, and additional data from the expedition will soon be made publicly available by the IODP.
References :
Kodaira, S., M. Conin, P. Fulton, J. Kirkpatrick, C. Regalla, K. Ujiie, N. Okutsu, L. Maeda, S. Toczko, N. Eguchi, 2025.
Tracking Tsunamigenic Slip Across the Japan Trench (JTRACK)
Proc. IODP, 405.
Chester, F. M., J. Mori, N. Eguchi, S. Toczko, Expedition 343/343T Scientists, 2013.
Structure and composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake Science, 342, 1208–1211.
Ujiie, K., H. Tanaka, T. Saito, A. Tsutsumi, J. J. Mori, J. Kameda, E. E. Brodsky, F. M. Chester, N. Eguchi, S. Toczko, 2013.
Low coseismic shear stress on the Tohoku-Oki megathrust determined from laboratory experiments
Science, 342, 1211–1214.
Scientific contacts :
- P. Pei – Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, ISTerre
- Mai-Linh Doan - Professor, Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, ISTerre