Published by the American Geophysical Union as part of theGeophysical Monograph Series, Volume 143.For thousands of years man has marvelled at the giganticstructure that makes up Mt. Etna, the largest active volcano inEurope, and has lived side by side with the mountain, which despiteits intense eruptive activity has always been considered a“friendly giant.”After the Second World War, with its frequent but nonlife-threatening eruptions, Mt. Etna represented an ideal locationfor volcanological research for the national and internationalscientific community. Numerous scientists from Belgium, Germany,France, the United Kingdom, and the United States of America havetaken part in volcanological research aimed at understanding thevolcano.