Coupled simulation of landslide, tsunami, and ground displacement for the 2017 Nuugaatsiaq event in Greenland

Abstract. We investigated the entire sequence of the tsunami event caused by a large landslide that occurred on 17 June 2017, in Karrat Fjord near Nuugaatsiaq village in western Greenland, and clarified the sequential processes of this cascading phenomenon. The volume of the landslide was estimated about 44 × 106 m3 based on seismological analysis at seven observation stations across Greenland and an empirical relation. We conducted sequential simulations, consisting of (1) the landslide descent into the fjord based on topography, (2) tsunami generation and large-scale propagation, and (3) ground motion caused by water surface elevation due to the tsunami, considering both static and elasto-dynamic solutions. A 1 m water surface elevation causes ground displacement of up to 0.1–1.0 mm in coastal areas, and this can be detected by seismometers. This event provided a rare chance to verify the integrated model using only local seismic records in the case of no coastal tidal measurement. The timing of simulated processes agrees well with observations, but uncertainties in landslide volume remain a major factor affecting tsunami amplitude and coastal impact. The detailed seismic signals captured both near and far from the epicentre shed light on the multi-stage dynamics of such cascading phenomena. To monitor landslide occurrence and estimate potential tsunamis early, such analyses should be systematically conducted in real time and could be utilized in early warning systems.