We investigated the entire sequence of the tsunami event led by a massive landslide on June 17, 2017, in Karrat Fjord, near Nuugaatsiaq village, western Greenland to understand the causality of this cascade mechanism. The seismological analysis from seven stations across Greenland allows to estimate the landslide volume. Then, we conducted sequential simulations, consisting of (1) the landslide’s descent into the fjord based on topography, (2) tsunami generation and large-scale propagation, and (3) ground deformation caused by tsunami-induced sea level changes, considering both static and elasto-dynamic solutions. A 1 m-height of sea level change may lead to a ground deformation up to 0.1–1.0 mm along the coastline, and this can be detected by a seismogram. This event provided a rare chance to validate our integrated model using local seismic records alone in the case of no coastal measurement. While the timing of simulated processes matches observations well, uncertainties in landslide volume remain a key factor influencing tsunami amplitude and coastal impact. The detailed seismic signals captured both near and far from the source shed light on the multi-stage dynamics of such cascading events and offer valuable input for improving hazard assessment in fjord-like environments, and suggests that alert systems based on seismic data are feasible, allowing to reduce tsunami risks in fjords in polar regions.