High resolution tsunami inundation maps: towards multi-hazard risk analysis.

Multi-hazard disaster risk analyses in coastal areas requires the integration of data and models concerning hazard, exposure and vulnerability data and models, all developed with high spatial resolution. Indeed, accurate high-resolution models and data are essential for properly assessing the impact of specific hazards that threaten coastal areas, such as tsunamis, floods, landslides, and coastal erosion. Nevertheless, this level of detail remains unachieved for many coastal hazards in various locations. Consequently, critical fine-scale differences in localized risk assessment are overlooked, leading to potential underestimations or overestimations of the actual risk to coastal communities. It is vital to address this gap in order to enhance the accuracy and reliability of risk assessments.

A key step in tsunami hazard and risk assessment involves the development of inundation maps, specifically maps describing inundated areas and related depths. To date, such maps are not yet available at proper resolution for the coastal areas of the Friuli-Venezia-Giulia Region (FVG). Accordingly, this study aims to enhance the characterization of tsunami hazard in the Northern Adriatic by developing detailed inundation maps and possibly addressing the identified research gaps. Leveraging on accurate and high resolution bathymetry and topographic data is crucial for reliable tsunami modelling for the FVG coastal areas. To this purpose, bathymetry and topographic data are refined and are used, along with existing databases of tsunamigenic earthquake sources, for modelling tsunami waves propagation and inundation by means of the NAMI DANCE code (e.g. Yalciner et al. 2014, Mediterranean Sea Oceanography and references therein).

Existing datasets from open access and local data sources are collected and then refined, particularly addressing inaccuracies in lagoon bathymetry. This involves incorporating high-resolution data and considering small-scale coastal features that can significantly impact tsunami inundation. Multiple bathymetry and topography datasets are used to develop high resolution refined data at 25 meters, and 10 meters resolution. The database of co-seismic seafloor displacement for all individual scenarios, developed based upon the DISS-3.3.0 database, is adopted to carry out a reappraisal of tsunami wave amplitude maps (Peresan & Hassan, MEGR 2024 and references therein) and to estimate realistic tsunami inundation maps. Additionally, tsunami sources caused by local earthquakes relevant to the FVG region are investigated, providing local scale maps of wave amplitudes and inundation estimates; this involves using appropriate fault rupture realisations for local tsunami scenarios (ITCS100&101), as specified in the DISS-3.3.0 database.

The outcomes from this study provide the basis for multi-scenario tsunami hazard assessment, contributing to the development of high-resolution and comprehensive tsunami hazard maps for the Northern Adriatic coasts. Moreover, along with high-resolution exposure maps, they contribute improving precision and accuracy of related risk assessment, and hence are an important step in preparedness, response, and prevention efforts in the framework of disaster risk management.

This research is a contribution to the RETURN Extended Partnership (European Union Next-Generation EU—National Recovery and Resilience Plan—NRRP, Mission 4, Component 2, Investment 1.3—D.D. 1243 2/8/2022, PE0000005).