Evidences of two Holocene phreatomagmatic eruptions at Stromboli volcano (Aeolian Islands) from paleomagnetic data

We present detailed stratigraphic-sedimentological and paleomagnetic analyses of Holocene phreatomagmatic deposits at Stromboli volcano (Aeolian Islands, Italy). The investigated deposits belong to the Secche di Lazzaro succession (SDL) and to the Advanced Operations Center of the Department of Civil Defense (COA) succession, both lying on the Neostromboli lavas (ca. 13–5 ka). The two stratigraphic successions have similar stratigraphic position and show a phreatomagmatic origin, likely related to catastrophic magma-water interaction processes during sector collapse events. However the thermal remanent magnetization data of the lava lithics indicate that deposits of the SDL succession were emplaced at very low temperatures (less than 140C), whereas the basal part of the COA deposit was emplaced at temperatures between 300–340C. Paleomagnetic results indicate that the two investigated deposits may be related to two distinct eruptive events occurred during the Holocene. Recent phreatomagmatic activity at Stromboli apparently has occurred more frequently than previously believed. Consequently, we must reconsider the recurrence interval of this dangerous eruptive scenario for Stromboli.