Current knowledge of Etna's flank eruptions (Italy) occurring over the past 2500 years. From the iconographies of the XVII century to modern geological cartography

Abstract

Knowledge of Etna's eruptions has been profoundly influenced by the illustrations, though these can only provide limited information on the lava flows and their effects on the territory. Indeed, the absence of iconographic sources or again the disparity between the physical reality and the illustrations has led to many gaps and uncertainties that have lasted for centuries. This paper traces the progress of the representations of the historical eruptions of Etna volcano, fromthe earliest attempts in the 17th century, be they iconographic documents or pictorial illustrations, to themodern geological cartography of 21st century. It seeks to reconstruct the evolution of the history and methods of representing Etnean eruptions, highlighting the crucial steps in the progress of knowledge on the historical flank eruptions. The turning point in the long process of drawing and rendering the eruptions of Etna came with the work of Sartorius vonWaltershausen, with the realization of the first geological map of the volcano at a 1:50,000 scale between 1836 and 1843. In this long history of the representations of eruptions, begun in the 17th century, Sartorius' cartography finally overcame the problem of rendering these events in space by inserting the notion of history in the map.What now remained for those engaged in mapping the volcano was to solve the issue of defining the “time” of Etna's historical lava flows. Thiswould be tackled only at the end of the 20th centurywith a multidisciplinary approach comprising stratigraphy, historiographical studies and the dating of the lavas. In this frame, the present state of the knowledge of the flank eruptions occurring on Etna in the past 2500 year has evidenced that during the Greek-Roman and Medieval epochs up to the 17th century flank eruptions commonly involved the middle-lower slopes, impacting mainly the south sector of the volcano with the location of the eruptive fissure sometimes below 1000 m of altitude. This eruptive behavior of the volcano has been radically modified following the occurrence of the large 1669 eruptions since the opening of the fissures was mainly concentrated in the upper-middle slopes between 1600 m and 2500 m a.s.l.