A heuristic features selection approach for scenario analysis in a regional seismic probabilistic tsunami hazard assessment

Seismic Probabilistic Tsunami Hazard Analysis (SPTHA) is aimed at estimating the annual rate of
exceedance of an earthquake-induced tsunami wave of a certain location with reference to a
predefined height threshold. The analysis relies on computationally demanding numerical sim ulations of seismic-induced tsunami wave generation and propagation. A large number of sce narios needs to be simulated to account for uncertainties. However, the exceedance of tsunami
wave threshold height is a rare event so that most of the simulated scenarios bring little statistical
contribution to the estimation of the annual rate yet increasing the computational burden. To
efficiently address this issue, we propose a wrapper-based heuristic approach to select the set of
most relevant features of the seismic model, for deciding a priori the seismic scenarios to be
simulated. The proposed approach is based on a Multi-Objective Differential Evolution Algorithm
(MODEA) and is developed with reference to a case study whose objective is calculating the
annual rate of threshold exceedance of the height of tsunami waves caused by subduction
earthquakes that might be generated on a section of the Hellenic Arc, and propagated to a set of
target sites: Siracusa, on the eastern coast of Sicily, Crotone, on the southern coast of Calabria,
and Santa Maria di Leuca, on the southern coast of Puglia. The results show that, in all cases, the
proposed approach allows a reduction of 95% of the number of scenarios with half of the features
to be considered, and with no appreciable loss of accuracy.