Quantifying Tsunami Hazard for the Northeastern Adriatic Coasts: A Multi-Scenario Approach

Significant earthquake-induced tsunamis in Northern Adriatic are rare and only a few historical events were reported in the literature, with sources mostly located along with central and southern parts of the Adriatic coasts. Recently, a tsunami alert system has been established for the whole Mediterranean area; however, a detailed description of the potential impact of tsunami waves on coastal areas is still missing for several sites. This study aims at modelling the hazard associated with possible tsunamis, generated by offshore earthquakes, with the purpose of contributing to tsunami risk assessment for selected urban areas located along the Northeastern Adriatic coasts. Tsunami modelling is performed by the NAMI DANCE software, which allows accounting for seismic source properties, variable bathymetry, and non-linear effects in wave’s propagation.

Preliminary hazard scenarios at the shoreline are developed for the coastal areas of Northeastern Italy and at selected cities (namely Trieste, Monfalcone, Lignano and Grado). A wide set of potential earthquake-induced tsunamis, located in three distance ranges (namely at Adriatic-wide, regional and local scales), are considered for the modelling; sources are defined according to available literature, which includes catalogues of historical tsunami and existing active faults databases. Accordingly, a preliminary set of tsunami-related parameters and maps are obtained (e.g. arrival times, maximum wave amplitude, synthetic mareograms), relevant towards planning emergency and mitigation actions at the selected sites.

In addition, a fully formalized operational procedure for time-dependent seismic hazard scenarios has been developed during the last two decades, which integrates earthquake forecasting information from pattern recognition analysis (CN algorithm), with the realistic modeling of seismic waves propagation by the neo-deterministic approach (NDSHA). For offshore large earthquakes, this integrated approach can be naturally extended to the definition of time-dependent tsunami scenarios, based on physical models of tsunami waves propagation. We review the outcomes from its applicaton for the recent events that occurred in the Adriatic region (namely: Durres, Albania 2019; Pesaro, Italy 2022), which support the possibility of developing time-dependent tsunamis scenarios, by integrating earthquake forecasts with the physical modelling of tsunami waves propagation.