Characterization of the tephra fallouts from Mount Etna 2013- 2015 lava fountains Simon Bufféral, Boris Behncke, (Pierre Briole) Abstract During the last years, EtnaŠs slopes have been covered several times by thick deposits of volcanic material (tephras), traducing a growing explosive eruptive behavior of the volcano. Right after every event, tephras were systematically sampled in the urban areas surrounding the volcano (at ≈ 20 km from the summit). Indeed, 5 deposits on the roads are cleaned between the fallouts, allowing each time to collect very well time-constrained samples. However, sampling has not been systematic on the slopes of the volcano. There, deposits are accumulating, forming a thick coat that anybody who wouldnŠt have monitored attentively the volcano could easily assume as the product of one single cataclysmic 10 eruption. In this context of repeated fallouts, only a precise study of the deposit al- lows to associate each layer to one time-constrained distal sample, and thus to the eruptive event which gave it birth. Eventually, this characterization of the diferences between two layers could show a common pattern allow- 15 ing to discriminate these diferences from those within the thick deposit of one single subplinian eruption. Tephra fallout direction depends on wind, and the layering is very vulnerable to washing by rain, erosion by wind and compaction by snow, so that few eruptive events are actually represented in this deposit. However, all this represents a large-scale study, requiring a 20 preliminary knowledge of the eruptive mechanisms giving rise to tephra fall- out, a good acquaintance with last years eruptions, as well as the awareness 1