Probabilistic hazard modeling of secondary pyroclastic avalanches generated by paroxysms at Stromboli (Italy)

Abstract

The remobilization and avalanching of fresh pyroclastic deposits are relatively common at Stromboli. They are usually confined to the Sciara del Fuoco (SdF), a steep depression on the northwestern side of the island. However, at least during the Strombolian paroxysms in 1944, 1930, and possibly in 1906, pyroclastic avalanches occurred out of SdF, flowed in the valleys on the volcano flanks, inundated regions at low elevation, and, finally, they reached the sea and produced vaste temporary deltas. In particular, in the 1930 event, the pyroclastic avalanche reached San Vincenzo village, causing victims and damage to the buildings. In this study we perform an uncertainty quantification on the inputs of the 2D depth-averaged model, preliminary to a comparison with the available field data. In particular, because the source location of the flow is also assumed uncertain, we adopt a simplified source zonation based on the analysis of topographic slopes, distance from the eruptive craters, and watersheds basins in the upper part of the island, where thick tephra deposits could more likely accumulate during a future paroxysm.