Probabilistic seismic hazard assessment in the Mt. Etna region (Italy): application to local volcano-tectonic earthquakes

Abstract

Earthquakes are, by far, the most relevant source of hazard for the densely urbanised areas of Mt. Etna region. Local communities living in the eastern and southern flanks of the volcano continuously suffer social and economic losses due to the very high occurrence of damaging earthquakes, which produce intensities up to degree X EMS despite of low energy (M < 5.0). Seismic hazard in the Mt. Etna region is controlled by two distinct types of earthquakes, namely regional and local events, which have different magnitudes and frequencies (Azzaro et al., 2008). In particular, hazard deriving from local volcano-tectonic events can be relevant if short exposure times (30 years) are considered, since the reference intensity (Iref) calculated at the exceeding probability of 10% reaches, in some localities, the IX degree (Azzaro et al., 2008; Azzaro et al., 2013). In the framework of the UPStrat-MAFA project, the seismic hazard was performed following the probabilistic approach (PSHA) based on historical macroseismic data, by using the SASHA code (D'Amico and Albarello, 2008; Albarello and D’Amico, 2013) which has been implemented in the project itself. This approach uses intensity site observations to compute the seismic history for each investigated locality; results are obtained in terms of maximum expected intensity with an exceedance probability ≥ 10% for a given exposure time. In this study we produced PSHA maps referred to local volcano-tectonic seismicity.