The 15 March 2007 explosive crisis at Stromboli volcano, Italy: Assessing physical parameters through a multidisciplinary approach

Pistolesi, M.

;Donne, D. Delle;Pioli, L.;Rosi, M.;Ripepe, M.

2011-01-01

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Abstract

Basaltic volcanoes are dominated by lava emission and mild explosive activity. Nevertheless, many basaltic systems exhibit, from time to time, poorly documented and little-understood violent explosions. A short-lived, multiblast explosive crisis (paroxysmal explosion) occurred on 15 March 2007 during an effusive eruptive crisis at Stromboli (Italy). The explosive crisis, which started at 20:38:14 UT, had a total duration of ∼5 min. The combined use of multiparametric data collected by the permanent instrumental networks (seismic, acoustic, and thermal records) and a field survey carried out immediately after the event enabled us to constrain the eruptive dynamics and quantify physical parameters. The eruption consisted of three major pulses: In the first, lithic blocks and ash were ejected at speeds of 100-155 m/s and 130-210 m/s, respectively. The high solid load of the eruptive jet resulted in the partial collapse of the column with the formation of a small-volume pyroclastic density current. The second, 12 s long pulse emitted 2.2-2.7 × 107 kg of tephra (mass discharge rate = 1.9-2.3 × 106 kg/s), forming a 3km high convective plume, dispersing tephra up to the west coast, and a dilute density current with limited dispersal downslope of the craters. A final, 30s long phase formed a scoria flow with a volume of 1.5-1.7 × 104 m3 (mass discharge rate = 5.9-6.7 × 105 kg/s), a total runout of ∼ 200 m, and a velocity of 45m/s. The total gas volume involved in the explosion was 1.3-1.9 × 104 m3 with an initial overpressure of 7.9 ± 0.4 MPa. We compared the 15 March 2007 event with historical paroxysms, in particular with that of 5 April 2003, which was remarkably similar.