No abstract

Catalogues from 1582 to the present of Etnean eruptions and earthquakes from various structural zones of southern Italy have been statistically compared using non-stationary Poisson statistics in order to search for correlative seismic and eruptive activity. A significant relationship exists between flank eruptions and earthquakes in the zone immediately surrounding the volcano. Also, crater eruptions are found to occur before flank eruptions which are not preceded by earthquakes. They do not, however, appear to be correlated with earthquakes. Earthquakes of different structural zones appear to be largely independent of each other.The results suggest two mechanisms for the flank eruptions of Etna. Those that are preceded by crater eruptions are presumed to be caused by magma pressure within Etna's storage reservoir. Whereas those preceded by earthquakes are thought to be due to fracturing of the flank by earthquakes caused by tensile forces associated with the east-west extension of eastern Sicily. The existence of earthquake-related volcanism is consistent with models which attribute Etna's existence to the extensional tectonism and lithospheric faulting in eastern Sicily. * by the normal faulting of the NE-SW Messina-Giardini tectonic line and the Tindari-Giardini NW-SE trending fault system. Ghisetti & Vezzani (1979) suggest that magma could reach the surface through the intersection of these lithospheric fault systems. Rittmann (1973) also attributes the volcano's existence to abyssal fissures caused by lithospheric extension of eastern Sicily. We investigate here the correlation between the 508

Abstract. Macroseismic studies, linear refraction profiles, and a two-dimensional seismic array study on Mount Etna, have all detected anomalous low velocity zones beneath the volcano. Seismic travel time delays together with high frequency attenuation observations confirm the presence of a large volume of partial melt beneath the volcano. A simplified three-dimensional model of the main storage system of Mount Etna is presented.