Uncertainty evaluation for the tsunami inundation zone in Italy

The Italian Tsunami Warning System (SiAM) is constituted by the Italian Civil Protection Department (DPC), the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Italian Institute for Environmental Protection and Research (ISPRA). In the frame of SiAM, the Italian Tsunami Warning Centre is established at the INGV, providing tsunami warning bulletins and supporting tsunami risk mitigation actions. The tsunami inundation zones supports long-term coastal planning and also the definition of evacuation maps to be used in case of a tsunami warning. The evacuation zones related to each alert level was defined by DPC based on a given level of acceptable risk that is by selecting the tsunami intensity of the hazard curve for the 2500 yr average return period at the 84th percentile of the epistemic uncertainty distribution of the Probabilistic Tsunami Hazard Analysis (PTHA) model. The regional Seismic PTHA developed in the TSUMAPS-NEAM project (http://www.tsumaps-neam.eu/) was adopted for this purpose. Despite the fact that numerical modeling is by far the most accredited tool to model tsunami propagation and inundation, the massive use of tsunami inundation simulations on high-resolution numerical grids of coastal areas still represents a challenge for practical applications. As an alternative, in TSUMAPS-NEAM the maximum run-up and inundation distance were estimated using statistical techniques and a GIS-based approach that convert referenced maximum run-up values into inundation lines, applying an inundation dissipation model obtained with empirical methods. T he aim of the present work is to evaluate the uncertainty of the inundation maps in a specific target area along the coastal segment between Catania and Siracusa, two touristic and commercial urban areas placed in southeastern Sicily, Italy which have experienced destructive tsunamis in the past. An appropriate set of tsunami scenarios representing the TSUMAPS-NEAM regional hazard for the target area were selected and modeled using high resolution tsunami numerical inundation simulations with Tsunami-HySEA, a non-linear hydrostatic shallow-water multi-GPU code.

This work was funded by the TSUMAPS-NEAM (Grant agreement ECHO/SUB/2015/718568/PREV26) project and the Agreement between INGV and DPC.