GNGTS 2013 - Atti del 32° Convegno Nazionale

Tests have been performed to evaluate the completeness of the catalogue and consequently a completeness magnitude Md = 2.5 has been obtained. According to this result, all further analysis have been carried out by selecting the earthquakes having such magnitude threshold and an hypocentre location uncertainty lower than 2.5 km, therefore obtaining a revised final dataset consisting of 2,762 earthquakes (Fig. 1a). Three different patterns of hypocenter distributions can be observed (Fig. 1b), therefore in order to obtain information about the Fig. 1 – a) Epicentre location of earthquakes with magnitude Md > 2.5 occurring between 1976 and 2011 at Mt. Etna; circle size indicates magnitude classes; colours indicate the depth range (see inset b for details); black lines indicate the main faults: PF (Pernicana fault system), RFS (Ragalna fault system), TFS (Timpe fault system), TCF (Trecastagni fault), TMF (Tremestieri fault) (modified from Azzaro et al. , 2012); b) number of earthquakes vs. focal depth; c) structural settings of eastern Sicily; d) daily and cumulative number of earthquakes during the study period; the size of the red and blue bands indicates the duration of the flank and the summit eruptions, respectively (Andronico and Lodato, 2005; Bullettin data from http://www.ct.ingv.it/it/banca-dati-delle-eruzioni/ eruzioni-etna.html). 279 GNGTS 2013 S essione 1.3