The December 2002 Stromboli tsunami: an accidental occurrence or a structural source of hazard?

The December 2002 slides at Stromboli, though characterized by small volume, generated considerable tsunami waves that hit all the coasts of the island in less than 3-4 minutes, and even reached 10 m height in certain places. Also the Island of Panarea was severely affected by the tsunami, that was observed as far as the Campania coasts, but did not provoke considerable effects elsewhere. The landslides and the consequent tsunamis occurred during a paroxistic crisis of the volcano. This paper shows that the 2002 tsunamis cannot be considered accidental occurrences, but rather events that can repeat since they are related to the structure and dynamics of the volcano. In the recent eruptive history of Stromboli most of the paroxistic episodes were accompanied by observed tsunamis. In addition one can also mention that the identified flank collapses of the volcanic edifice, the last of which left the Sciara del Fuoco scar in the Holocene, produced very probably large tsunamis. The paper shows examples of small-scale and large-scale tsunamis associated respectively to various medium range landslides detaching from the submarine slopes of the volcano and to the Holocene sector collapse. In view of our analysis, the Sciara del Fuoco area can be considered as the main source of hazard for the Stromboli coasts, not only for catastrophic events but also for medium-range events like the 2002 ones.