Probabilistic Tsunami Hazard Assessment for Messina Strait Area (Sicily, Italy)

The general modular Bayesian procedure is applied to provide a probabilistic
tsunami hazard assessment (PTHA) for the Messina Strait Area (MSA), Italy. This is the
first study in an Italian area where the potential tsunamigenic events caused by both
submarine seismic sources (SSSs) and submarine mass failures (SMFs) are examined in a
probabilistic assessment. The SSSs are localized on active faults in MSA as indicated by
the instrumental data of the catalogue of the Italian seismicity; the SMFs are spatially
identified using their propensity to failure in the Ionian and Tyrrhenian Seas on the basis of
mean slope and mean depth, and using marine geology background knowledge. In both
cases the associated probability of occurrence is provided. The run-ups were calculated at
key sites that are main cities and/or important sites along the Eastern Sicily and the
Southern Calabria coasts where tsunami events were recorded in the past. The posterior
probability distribution combines the prior probability and the likelihood calculated in the
MSA. The prior probability is based on the physical model of the tsunami process, and the
likelihood is based on the historical data collected by the historical catalogues, background
knowledge, and marine geological information. The posterior SSSs and SMFs tsunami
probabilities are comparable and are combined to produce a final probability for a full
PTHA in MSA.