Forecasting Eruptive Activity at Mt. Etna (Sicily): the May 2008 - July 2009 Case Study

Abstract

Mt. Etna is one of the most active volcanoes on the Earth, and a population of almost one million of people settle on its flank. Volcanic activity mainly consists of effusive and explosive paroxysmal activity both from its summit craters and new vents opened on the flanks along NE and S rift zones. Many villages and areas have been repeatedly invaded by lava flows during the historical period, posing the volcano hazard vulnerability assessment as a key feature in volcanology. Nowadays, volcanic activity is explored and supervised by an integrating multi-parametric monitoring approach such as to retrieve quantitative probabilistic estimates at both short- and long-temporal window and forecast impending eruptive activity. A successfully application of this approach was achieved by Brancato et al. (2011, 2012) by applying the BET_EF probabilistic code (Bayesian Event Tree_Eruption Forecasting; Figure 1). In the framework of the European Project MEDiterranean Supersite Volcanoes (MED-SUV), we show the results of BET_EF application in the flank eruptive activity occurred at Mt. Etna between May 2008 and July 2009. An inventory of seismic data, bulk SO2 flux, and microgravity collected in the period May 2007 – May 2008, was processed in a novel scenario of concept of inertia time window. Processed data provided outcomes fundamental for making objective and/or false predictions. Results clearly show the fundamental role of the monitoring data in defining key-stages of eruptive sequences, based on identification of thresholds.