7050 20241106120533.0 10.1126/science.adm9247 DOI SCART-2024-0158 Svennevig, K. A rockslide-generated tsunami in a Greenland fjord rang Earth for 9 days 2024 Climate change is increasingly predisposing polar regions to large landslides. Tsunamigenic landslides have occurred recently in Greenland (Kalaallit Nunaat), but none have been reported from the eastern fjords. In September 2023, we detected the start of a 9-day-long, global 10.88-millihertz (92-second) monochromatic very-long-period (VLP) seismic signal, originating from East Greenland. In this study, we demonstrate how this event started with a glacial thinning–induced rock-ice avalanche of 25 × 106 cubic meters plunging into Dickson Fjord, triggering a 200-meter-high tsunami. Simulations show that the tsunami stabilized into a 7-meter-high long-duration seiche with a frequency (11.45 millihertz) and slow amplitude decay that were nearly identical to the seismic signal. An oscillating, fjord-transverse single force with a maximum amplitude of 5 × 1011 newtons reproduced the seismic amplitudes and their radiation pattern relative to the fjord, demonstrating how a seiche directly caused the 9-day-long seismic signal. Our findings highlight how climate change is causing cascading, hazardous feedbacks between the cryosphere, hydrosphere, and lithosphere. BRAIN/ 2/ 191/P1/GEOCAMB NO rockslide landslide seismology tsunami seiche polar regions Hicks, S.P. Forbriger, T. Lecocq, T. Widmer-Schnidrig, R. Mangeney, A. Hibert, C. Korsgaard, N.J. Lucas, A. Satriano, C. Anthony, R.E. Mordret, A. Schippkus, S. Rysgaard, S. Boone, W. Gibbons, S.J. Cook, K.L. Glimsdal, S. Løvholt, F. Van Noten, Koen Assink, J.D. Marboeuf, A. Lomax, A. Vanneste, K. Taira, T. Spagnolo, M. De Plaen, R. Koelemeijer, P. Ebeling, C. Cannata, A. Harcourt, W.D. Cornwell, D.G. Caudron, C. Poli, P. Bernard, P. Larose, E. Stutzmann, E. Voss, P.H. Lund, B. Cannavo, F. Castro-Díaz, M.J. Chaves, E. Dahl-Jensen, T. Pinho Dias, N.D. Déprez, A. Develter, R. Dreger, D. Evers, L.G. Fernández-Nieto, E.D. Ferreira, A.M.G. Funning, G. Gabriel, A.-A. Hendrickx, M. Kafka, A.L. Keiding, M. Kerby, J. Khan, S.A. Dideriksen, A.K. Lamb, O.D. Larsen, T.B. Lipovsky, B. Magdalena, I. Malet, J.-P. Myrup, M. Rivera, L. Ruiz-Castillo, E. Wetter, S. Wirtz, B. Science 385 2024 1196–1205 thomas.lecocq@ksb-orb.be 16730489 http://publi2-as.oma.be/record/7050/files/MainManuscript_Dickson Fjord_copyeditcleaned.pdf 4266 http://publi2-as.oma.be/record/7050/files/MainManuscript_Dickson Fjord_copyeditcleaned.jpg?subformat=icon-180 icon-180 4862 http://publi2-as.oma.be/record/7050/files/MainManuscript_Dickson Fjord_copyeditcleaned.gif?subformat=icon icon 6039617 http://publi2-as.oma.be/record/7050/files/DicksonFjd4-LR1.gif Before & After view - The 25 million m³ rock mass fell into the fjord and generated a tsunami and a seiche that lasted for 9 days... 1156793 http://publi2-as.oma.be/record/7050/files/DicksonFjd4-LR1.gif?subformat=icon icon Before & After view - The 25 million m³ rock mass fell into the fjord and generated a tsunami and a seiche that lasted for 9 days... https://doi.org/10.1126/science.adm9247 https://youtu.be/60T9TKuuujs published in REFERD