The last Vesuvius eruption in March 1944: reconstruction of the eruptive dynamic and its impact on the environment and people through witness reports and volcanological evidence

Mount Vesuvius last erupted in March 1944. The eruption began with a modest effusive activity (18–21 March, phase I) and then moved on to a lava-fountain phase (21–22 March, phase II) that quickly culminated in a 24-h paroxysmal phase (22–23 March, phase III), during which the eruptive column reached its maximum altitude and ash carried by the wind was deposited at distances of up to 500 km from the volcano. Subsequently (phase IV), the ash cloud reached altitudes not exceeding 2 km above the crater and the explosions became discontinuous, alternating with frequent tremors. From April 7th the vent remained permanently closed. Since then, the current period of quiescence may be said to have begun. In our study we present a detailed geochemical study of the volcanic products emitted throughout the stages of the eruption, including an extreme distal ash sample, collected at the time of the eruption in Albania (Devoli) by the geologist Antonio Lazzari. The results indicate that magmatic differentiation took place in two crystallization stages under different temperature and pressure. Moreover, through the use of a numerical model of volcanic ash dispersion in the atmosphere as well as the collection of new witness accounts, we inferred the maximum height reached by the eruptive column (>8–10 km above the crater) as well as its impact on the environment and people, suggesting that the damage in the area and even the number of the victims could be higher than accepted until now.