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[1] Samples of scoriae erupted at Stromboli volcano during its persistent strombolian activity were collected between 2005 and 2008. Chemical and mineralogical compositions were obtained on products erupted from the three main crater sectors (SW, Central and NE). Small chemical variations indicate a different degree of evolution coupled with small difference of magma temperature

[1] Knowledge of past precursor patterns is crucial for the correct interpretation of monitoring data and reliable volcano forecasting. In the case of Vesuvius, one of the world's riskiest volcanoes, very little information is available about unrest signals following long periods of quiescence. The translation and analysis of three Latin treatises written from eye-witnesses immediately after the A.D. 1631 subplinian eruption allowed us to reconstruct the sequence of precursors. The progression in the signals was remarkably clear starting at least two to three weeks before the event. Widespread gas emission from the ground coupled with deformation was followed by an increase in seismic activity in the eight days before the eruption. Seismicity escalated both in frequency and intensity in the night before the eruption, heralding the opening of fissures on the volcanic cone. The details of phenomena occurring in the medium-term (months before the eruption) are difficult to evaluate, though it is worth noticing that no major tectonic earthquakes were felt in the area of the volcano. Civil protection preparedness plans should be organized in order to complete the evacuation of people in a time span significantly shorter than the duration of expected short-term precursors.

[1] The 5 April 2003 paroxysm of Stromboli occurred during an ongoing effusive episode that initiated on 28 December 2002. It mainly consisted in two, a few seconds apart cannon-like explosions followed by a vertical gas/pyroclast jet. The HK-basaltic pumices, that were generated, mainly contain crystals that were drained back from the shallow parts of the plumbing system. Few euhedral to anhedral olivines and their melt inclusions testify to crystal fractionation and possible mixing between HK-basaltic magmas variable in their volatile content, extent of evolution and volume. The most primitive, volatile-rich, HK-basalt term is sizable at micrometer scale, only. We propose that the triggering mechanism of the paroxysm was initiated at moderate pressures (≥240 MPa) and was related to bubble-driven ascent of magma blobs. The latter rose through and interacted with overlying slightly more evolved melts and, finally mingled with the shallow crystal-rich magma just before the eruption.

[1] The “large sample method” of archeomagnetic dating was applied to Stromboli. 127 samples (10 sites) yielded paleofield directions with 95% confidence intervals less than 2°. Coupled with a reference curve for secular variation in western Europe, these allow accurate dating of volcanic events. A lava flow underlying San Bartolo village gave a minimum age of AD 100 (±100); a lava overflow predating the last sector collapse was dated from 1350 (±60), suggesting the recent occurrence of highly hazardous events. Lava spatters and a hot avalanche high on the northern flank were emplaced during the XXth century; lava spatters on the lower flanks could date the onset of the still-ongoing phase from AD 550 (±50). These results are different from those obtained in a recent study, probably because traditional paleomagnetic sampling cannot yield sufficient precision, considering the characteristics of the archeomagnetic secular variation curve.