Fig. 4: Dispersal of tephra fallouts from both paroxysms.
From: Uncovering the eruptive patterns of the 2019 double paroxysm eruption crisis of Stromboli volcano
a The mass load of the fallout deposit of 3 July measured at 16 locations (red points), and observed (red lines) and simulated (black lines contouring pink-shaded areas, modeled by PLUME-MoM-TSM/HYSPLIT) isomasses. The deposit is simulated at 18:00 UTC (more than three hours after the explosion) and reveals a maximum ground load of about 30 kg m−2. Circled numbers indicate 6 high-risk sites considered in the discussion. Estimated dispersal area (blue lines), and isopleths of the maximum lapilli size (dotted blue lines, see “Methods” section) of the 28 August fallout deposit. Isopleths were interpolated based on data collected from 17 locations (blue circles; Supplementary Table 3). b–e Comparison of simulated (sim) and observed (obs) grain-size distributions at three sampling points (P01, P13, and P16), and Initial Total Grain-Size Distribution (TGSD) at the volcanic vent resulting from the inversion of the data for the 3 July paroxysm. f–h Observed grain-size distribution of three samples of the 28 August tephra fallout (LAB, CEM, SCA); on the basis of observations of the eruption by a witness, the sample collected at Labronzo is affected by the contribution of fine ash due to the elutriated cloud produced by the PDC.
