Sei qui: Home > News > Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Figure 1
Photos (a),(b),(c) and (d) illustrate successive moments of the collapse and related PDC emplacement from the INGV thermal camera located at Punta dei Corvi, the SW side of the Sciara del Fuoco (SdF); the arrow indicates the NE craters, and the white dashed line indicates the shoreline. (a) represents the early stage of the collapse, and the cold dust is visible above the SdF, lifted up by the continuous rock falls lasting a few hours. (b) the PDC is visible running down the SdF, propagating offshore above the seawater table (c), and a small accretion fan besides the shoreline. The interaction with the warm PDC and the cold marine water caused hydromagmatic explosions, with flares visible in (c). In (d) the rising ash-cloud can be seen; there is a portion along the SdF that is elutriated from the PDC, and a portion offshore produced by the hydromagmatic explosion triggered after the PDC water interaction (see the high temperature burst in c). (e),

Re G., M. Pompilio, P. Del Carlo and A. Di Roberto (2022).
Sci. Rep., 12, 1–15,


We report on the ash cloud related to the gravitational collapse of a portion of the Stromboli volcano crater rim that occurred on 19 May 2021. The collapse produced a pyroclastic density current (PDC) that spread along the northwest flank of the volcano and propagated in the sea for about 1 km. The PDC was associated with a convective ash cloud that rapidly dispersed eastward and deposited a thin layer (< 1 mm) of very fine pinkish ash over the village of Stromboli. The deposit was sampled shortly after the emplacement (within a few hours) and prior to any significant reworking or re-sedimentation. We present a comprehensive description of the deposit including dispersal, sedimentological characteristics and textural and geochemical features. We also compare the 19 May 2021 deposit with fine-ash deposits connected to other PDCs and landslides previously occurring at Stromboli and with the distal ash of a paroxysmal explosive eruption of Mt. Etna volcano. Results indicate that the distributions of the mass on the ground and of the grain size are not correlated with the distance from the source. Also, the componentry reflects a preponderance of remobilized material ingested by the PDC. Therefore, the great amount of fine ash can be ascribed to clasts comminution processes, although the prevalence of dense crystalline components records an overall equiaxial shape, revealing a paucity of elongated clast with complex morphology. Furthermore, the outcomes of this work aim to create a collection of data of a co-PDC ash cloud that may prove useful for comparison with other deposits worldwide.