Climate change is preconditioning large landslides in polar regions. Tsunamigenic landslides have occurred recently in Greenland (Kalaallit Nunaat), but none are known from the east coast. On 16 September 2023, we observed an unprecedented up to 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 impacting Dickson Fjord, then triggering a 200 m high tsunami. Simulations show the tsunami stabilized into an 8 m- high long-duration seiche. The simulated seiche has a near-identical frequency to the seismic signal and a similarly ultra-slow decay. An oscillating, fjord-transverse single-force explains the seismic radiation pattern relative to the fjord. These findings show how the seiche, triggered by a ~100 s-long landslide, directly caused the 9-day long seismic signal. Ongoing warming will increase the frequency of these events and the risk posed by them.
These results are submitted for publication and are currently in review.
This repository contains codes used in our analysis and information required to prepare the figures in the manuscript and supplementary material.
The repository follows the structure of the manuscript, where codes and/or instructions and data sources are provided for each figure and its subplots:
fig1\: Seismic source, tsunami observations and modeling.
fig2\: Landslide observations.
fig3\: Landslide seismic signal and modelling.
fig4\: Very-Long-Period (VLP) seismic signal characteristics.
supplementary\: Figures in the supplementary materials.
bathymetry\: Detailed bathymetry of the Kempe Fjord area.