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Field Investigation and Numerical Modeling of Deposit-derived Pyroclastic Density Currents in Punta Labronzo Area (Stromboli, Italy), from the Paroxysmal Activity of 1930

Lucas Corna1 , Andrea Bevilacqua1, Federico Di Traglia2, Alessio Di Roberto1, Augusto Neri1, Massimo Pompilio1, Giuseppe Re1, Alessandro Tadini1, Mattia de'Michieli Vitturi1

  • Affiliations: 1Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italia; 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italia 

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 180

  • Programme No: 3.9.15

  • Theme 3 > Session 9

Abstract

Stromboli volcano (Italy) typically exhibits a persistent, low-intensity, explosive activity originating from its craters, located at about 750 m elevation over Sciara del Fuoco, a horseshoe-shaped depression on the NW flank, ≈2 km from villages. A few times per decade, the volcano can produce more powerful explosions, called paroxysms, possibly accompanied by Pyroclastic Density Currents (PDCs) from deposit instability. Outside Sciara del Fuoco, deposit-derived PDCs during the paroxysms in 1930 affected the NE basins that open towards inhabited areas, and in 1944 invaded the unpopulated basins to the SE of the craters. This study focuses on a small drainage basin on the North flank, tens of meters from the side of Sciara del Fuoco and ≈1 km from Stromboli village. There, at less than 200 m elevation, recent floods unveiled a previously unknown ≈1 m thick mass flow deposit intercalated between two spatter layers of the 1930 eruption and containing charred vegetation. Although componentry and grain size analysis present similarities with the larger flows in San Bartolo, the field samples at Labronzo show remarkably preserved older ash pellets engulfed by the flow, some of which with an accretionary hull. By performing depth-averaged flow modelling, we tested different assumptions on the source area, initial thickness, and dissipation parameters, indicating a volume <104 m3 and independent dynamics from the other 1930 PDCs. A relatively low energy PDC synchronous to the fallout, would be consistent with historical observations of gravity flows of the hot deposits in the area.