A methodology for tsunami inundation numerical simulations relying on inputs from probabilistic databases

Abstract A new methodology to link datasets of regional Probabilistic Tsunami Hazard Assessment (PTHA) with inputs for numerical simulation site-specific tsunami inundation was developed. The present study focused on the NEAMTHM18, which is a PTHA database developed for earthquake-generated tsunamis mapping the North Eastern Atlantic, the Mediterranean, and connected seas coasts. This approach was motivated by the need to use PTHA frameworks as a foundation to provide boundary conditions to detailed tsunami inundation simulations. The proposed methodology was organised into three subsequent steps, starting from the definition of the hazard indicator. This step is followed by the definition of a finite set of incident free water surface time series after defining some additional hypotheses. Finally, inundation simulations were carried out and used as the basis of successive aggregated hazard maps. The methodology was demonstrated by applying it to the Messina Strait, focusing on three different interest areas, for which aggregated hazard maps were obtained and compared to simplified inundation maps already available from government agencies. These latter were shown to overestimate the inundation maps obtained with the high-resolution simulations, while at the same time being consistent. This highlighted the necessity of carrying out these additional studies when designing critical infrastructures. The prediction of more limited inundation areas in this study is then associated, in contrast to previously developed simplified inundation maps, to the ability of this new method to consider the effect of the coast with high resolution, which is essential for reliable hazard assessment. Additionally, this study also suggested that the use of the N-WAVE theory might be appropriate for these types of studies. The results were also qualitatively compared with historical data from the 1908 Messina Strait tsunami. Finally, the present study helps to highlight the needs of end users when conducting detailed tsunami modelling and infrastructure design, applying PTHA databases that have been already developed. These needs might then be used as foundational requirements for future developments of PTHA tools.