Issues in near-source probabilistic seismic hazard analysis of the Messina Strait (Italy): preliminary investigation
Ultima modifica: 2025-08-06
Sommario
Probabilistic seismic hazard analysis (PSHA), in its classical form, is a consolidated analytical tool that provides a rational basis for the definition of seismic input for structural design or assessment. One of the challenges that emerges for construction projects of strategic importance in the vicinity of known faults, is incorporating so-called near-source (NS) effects in PSHA. The most prominent NS effect with engineering relevance is that of rupture directivity, which can cause long-period coherent ground velocity pulses to manifest at sites aligned with the direction of rupture propagation, leading to peculiar elastic and inelastic spectral amplification effects. The present work examines such NS shaking scenarios for the Messina Strait, where the infamous 1908 M7.1 Messina earthquake occurred. More specifically, a NS-PSHA analysis is performed for potential construction sites in the vicinity of the Sicilian and Calabrian coast straddling the strait. This analysis uses fault geometry information from the database of individual seismogenic sources, which is curated by the Italian national institute of geophysics and volcanology, and accounts for the possible occurrence of impulsive ground motion by employing semi-empirical models from the literature. To account for the fact that fault-specific earthquake occurrence models may depart from the classical homogeneous Poisson process, adopted for larger seismic source zones, the NS-PSHA considers a series of time-variant models, including renewal and semi-Markovian stochastic processes. The results of this analysis are finally compared with those from classical PSHA based on large-scale source models.
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