Climate change is increasingly exposing polar regions to large landslides. Tsunamigenic landslides have occurred recently in Greenland, but none have been reported from the eastern fjords. In September 2023, we detected the start of a 9-day-long global 10.88 mHz (92 s) monochromatic very-long period (VLP) seismic signal, originating from East Greenland. We demonstrate how this event started with a 25 M m3 glacial thinning-induced rockslide plunging into Dickson Fjord, triggering a 200 m high tsunami. Simulations show the tsunami stabilized into a 7 m-high long-duration seiche with a near-identical frequency (11.45 mHz) and slow amplitude decay as the seismic signal. An oscillating, fjord-transverse single-force reproduces the seismic amplitudes and their radiation pattern relative to the fand lithosphere. The study was conducted by Svennevig et al. (2024) and published in Science. The paper is available here: https://www.science.org/doi/10.1126/science.adm9247 (and without the paywall here: https://drive.google.com/file/d/15HhsNkMb9x9Qc5wNWMNTzvLYceIXo04Z/view?usp=sharing). Music credit: "Seiche" by Isabelle Ryder (https://www.youtube.com/watch?v=H1xh1Pf5JvU; https://isabellerydermusic.weebly.com). Show more