A rockslide-generated tsunami in a Greenland fjord rang Earth for 9 days

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Abstract

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.

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Publication type Article
Publication Subtype Journal Article
Title A rockslide-generated tsunami in a Greenland fjord rang Earth for 9 days
Series title Science
DOI 10.1126/science.adm9247
Volume 385
Issue 6714
Year Published 2024
Language English
Publisher American Association for the Advancement of Science
Contributing office(s) Geologic Hazards Science Center - Seismology / Geomagnetism
Description 10 p.
First page 1196
Last page 1205
Country Greenland
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