Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2017-127
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
05 Apr 2017
Review status
This discussion paper is under review for the journal Natural Hazards and Earth System Sciences (NHESS).
When probabilistic seismic hazard climbs volcanoes: the Mt Etna case, Italy. Part I: model components for sources parametrization
Raffaele Azzaro1, Graziella Barberi1, Salvatore D'Amico1, Bruno Pace2, Laura Peruzza3, and Tiziana Tuvè1 1Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania – Osservatorio Etneo, 95123, Italy
2DiSPUTer, Università "G. d’Annunzio" Chieti-Pescara Via dei Vestini, Chieti, Italy
3Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS, Sgonico (TS), 34010, Italy
Abstract. The volcanic region of Mt Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment, given the availability of a long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitorings and especially because the very fast geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of Probabilistic Seismic Hazard Assessment (PSHA) whose first results and maps are presented in a companion paper, Peruzza et al. (2017). The sources include, in a picture of increasing complexity, area seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue that covers about three centuries, and a high-quality instrumental locations database for the last decades). The analysis of the frequency-magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude-size scaling relationship specific for this volcanic area, which was has been implemented into a recently developed software tool – FiSH, Pace et al. (2015) – which we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for Mt Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modelling, joined with a 3D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can be therefore implemented in PSHA maps. They can be relevant for the retrofitting of the existing building stock, and for driving risk reduction interventions. These analyses do not account regional M > 6 seismogenic sources which dominate the hazard at long exposure times (≥ 50 yrs).

Citation: Azzaro, R., Barberi, G., D'Amico, S., Pace, B., Peruzza, L., and Tuvè, T.: When probabilistic seismic hazard climbs volcanoes: the Mt Etna case, Italy. Part I: model components for sources parametrization, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-127, in review, 2017.
Raffaele Azzaro et al.
Raffaele Azzaro et al.
Raffaele Azzaro et al.

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