Relationship between seismicity and eruptive activity at Mt. Etna volcano (Italy) as inferred from historical record analysis: the 1883 and 1971 case histories

In this paper historical and recent seismological data are analysed in order to investigate the relationship between seismicity and eruptive phenomena at Mt. Etna volcano. The 1883 and 1971 case histories have been proposed because they are significant events in the recent history of the volcano regarding volcanic hazard and show very different evolutions of associated seismic activity and eruption dynamics. The first (1883) represents flank eruptions characterised by high seismic release, short duration and moderate effusion rate whereas the second (1971) can be ascribed to eruptions starting as summit or subterminal events and thereafter developing on the flanks with a minor level of seismicity, higher effusion rate and prolonged duration. The pattern of seismic activity during 1883 and 1971, as inferred from historical record analysis, and the different associated type of eruption may be a result of diverse stress conditions acting on the volcanic system. The interpretation of the seismic behaviour by considering historical eruptions in a systematic fashion will contribute to a clearer understanding of volcanic phenomena at Mt. Etna.