Karrat Fjord (Greenland) tsunamigenic landslide of 17 June 2017: initial 3D observations

On 17 June 2017, a landslide-generated tsunami reached the village of Nuugaatsiaq, Greenland, leaving four persons missing and presumed dead. Here, we present a preliminary high-resolution analysis of the tsunamigenic landslide scar based on three-dimensional (3D) reconstructions of oblique aerial photographs taken during a post-failure reconnaissance helicopter overflight. Through a 3D quantitative comparison with pre-failure topography, we estimate that approximately 58 million m(3) of rock and colluvium (talus) was mobilized during the landslide, 45 million m(3) of which reached the fjord, resulting in a destructive tsunami. We classify this event as a tsunamigenic extremely rapid rock avalanche, which likely released along a pre-existing metamorphic fabric, bounded laterally by slope-scale faults. Further analysis is required to properly characterize this landslide and adjacent unstable slopes, and to better understand the tsunami generation.