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Tsunamis are one of the most catastrophic natural hazards that can devastate coastal regions. Most common mechanisms that generate tsunamis are undersea earthquakes and submarine landslides. However, in enclosed basins, such as fjords, reservoirs, and lakes, subaerial landslides can also generate devastating tsunamis with similar or worse consequences, because of a more efficient wave generation. Here, we present the validation of a three-dimensional (3D) numerical model, TSUNAMI3D, by comparing numerical results with a set of subaerial landslide laboratory experiments carried out in the large tsunami wave basin at the Oregon State University (OSU). Results obtained from the laboratory experiments show that subaerial landslides generate highly non-linear waves with complex wave patterns and runup, challenging existing numerical models. The 3D numerical model is first verified with a commercial code, FLOW3D, to obtain a compromise between the model's spatial-time resolution accuracy and computational cost. Second, the 3D numerical model and the commercial code are validated with a set of OSU laboratory experiments comprising three different layouts or basin configurations, namely, fjord, curved headland, and basin-wide. Simplified material rheology and key parameters required for modeling subaerial landslides are defined. Numerical models' relative errors are estimated and analyzed, and the models' limitations are discussed. In general, numerical models' relative errors are found to be acceptable in most of the validation tests except those tests located close to the wave generation region. Validation results confirm that the 3D numerical models with simplified landslide rheology can be used to understand and reproduce the complex non-linear wave propagation and runup generated by subaerial landslides. Thus, TSUNAMI3D can help assess tsunami hazards in communities located in proximity to potential subaerial landslides. Also, the set of physical experiments can be used for further numerical validation efforts, helping tsunami organizations, e.g., the National Tsunami Hazard Mitigation Program, to amend existing or develop better numerical models and thus, improve inundation/evacuation mapping products that would save lives and property. [ABSTRACT FROM AUTHOR]

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 m3 of rock and colluvium (talus) was mobilized during the landslide, 45 million m3 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. [ABSTRACT FROM AUTHOR]