Assessment of the tsunamigenic potential of seamounts in the Tyrrhenian sea

While consolidated methodologies exist for tsunami hazard quantification related to seismic sources, hazard studies for other tsunamigenic sources are rare and are usually based on the analysis of specific scenarios. In fact, the generation and propagation of tsunamis produced by submarine landslides are complex processes that require specific knowledge about potential sources and sophisticated modeling of both the source and the tsunami generation and propagation. Given the scarcity of direct data for most of submarine structures and the high computational cost of sophisticated models, there are no systematic studies capable of quantifying the tsunamigenic potential of non-seismic sources over an entire basin while accounting for the full source variability. However, such sources may be significant, and may be even dominating in areas at low seismicity, such as the Tyrrhenian Sea, a geologically complex region hosting numerous submerged volcanic edifices in the central Mediterranean. Here, an innovative approach is developed to identify the most relevant tsunamigenic sources in terms of their potential impact on the surrounding coasts. A simplified modeling approach for the tsunamigenic source is developed and coupled with a nonlinear model for the subsequent tsunami propagation (Tsunami-HySEA). This model is tested and calibrated using well-known sources at Marsili volcano, modeled with a more complex model (Landslide-HySEA), which allows for fully coupled modeling of the landslide and the water body. The simplified model can be homogeneously applied to all the existing potential sources in a large source areas in order to quantify their tsunamigenic potential in terms of the maximum  at the coast. The results consist of non-trivial prioritization maps for each target area, allowing for the identification of the sources that deserve specific attention as they may potentially dominate the hazard at the target. Such prioritization maps may constitute a first fundamental step toward hazard quantification for such a type of source.