A case history of paroxysmal explosion at Stromboli: Timing and dynamics of the April 5, 2003 event

On April 5, 2003, Stromboli volcano (Italy) produced the most violent explosion of the past 50 years. The event was
exceptionally well documented thanks to the presence on the island of several scientists and a large number of instruments
deployed over the preceding months to monitor the effusive eruption that began in December 2002. Integration of visual
documentation, deposit features and geophysical data allowed an accurate reconstruction of the explosive event and its dynamics.
The eruption consisted of a 8-min long explosive event which evolved through four phases whose timing was precisely recorded by
an infrared thermometer located about 450 m from the summit crater. Phases 2 and 3 lasted 39 and 42 s, respectively. Both had an
impulsive character, were responsible for ejecting almost the entire mass of the pyroclastic products. Phases 1 and 4 represented,
respectively, a short-lived precursory event and a waning tale. During Phase 2, meter-sized ballistic blocks were launched with
velocities of 170 m/s to altitudes of up to 1400 m above the craters. These fell on the volcano flanks and on the village of Ginostra,
about 2 km distant from the vent. A vertical jet rose above the craters which developed to feed a convective plume that reached a
height of up to 4 km. The calculated mass of the Phase 2 fallout deposit and mass discharge rate were 1.1–1.4×108 kg and 2.8–
3.6×106 kg/s, respectively. During Phase 3 a scoria flow deposit, with an estimated volume of 0.9–1.1×104 m3, was erupted from
the same vent that fed the ongoing sustained lava flow. The average mass discharge rate for this phase was 2.5–3.1×105 kg/s.
Products emitted during Phases 2 and 3 consisted of lithic and fresh magmatic material in similar proportions. The juvenile
fraction consisted of a deep-originated, almost aphyric, highly vesicular pumice mingled with a shallow-derived, crystal-rich,
moderately vesicular scoria.
Similarities with the eruption dynamics of other historical paroxysms at Stromboli makes the April 5, 2003 explosion
representative of these highly energetic events that constitute the most hazardous volcanic phenomena at Stromboli volcano.

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Stromboli Island and impact on the south-east Tyrrhenian coasts,
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observation and thermal data, J. Volcanol. Geotherm. Res. 149
(2006) 160–175.
M.L. Carapezza, S. Inguaggiato, L. Brusca, M. Longo,
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31 (2004), doi:10.1029/2004GL020458.
M. Mattia, M. Rossi, F. Guglielmino, M. Aloisi, Y. Bock, The
shallow plumbing system of Stromboli island imaged from 1 Hz
instantaneous GPS positions, Geophys. Res. Lett. 31 (2004),
doi:10.1029/2004GL021281.
M. Ripepe, E. Marchetti, P. Poggi, A. Harris, A. Fiaschi, G.
Ulivieri, Seismic, acoustic, and thermal network monitors the
2003 eruption of Stromboli Volcano, Eos, Trans.-Am. Geophys.
Union 85 (2004) 329–332.
A. Harris, D. Pirie, K. Horton, H. Garbeil, E. Pilger, H. Ramm, R.
Hoblitt, C. Thornber, M. Ripepe, E. Marchetti, P. Poggi,
DUCKS: low cost thermal monitoring units for near-vent
deployment, J. Volcanol. Geotherm. Res. 143 (2005),
doi:10.1016/j.jvolgeores.2004.12.007.
A. Tibaldi, Multiple sector collapses at Stromboli volcano, Italy:
how they work, Bull. Volcanol. 63 (2001) 112–125.
M. Rosi, A. Betagnini, P. Landi, Onset of the persistent activity at
Stromboli volcano (Italy), Bull. Volcanol. 62 (2000) 294–300.
F. Barberi, M. Rosi, A. Sodi, Volcanic hazard assessment at
Stromboli volcano based on review of historical data, Acta
Vulcanol. 3 (1993) 173–187.
G. Mercalli, I vulcani attivi della Terra, Hoepli, Milan, 1907.
A. Rittmann, Der Ausbruch des Stromboli am 11 September
1930, Zeits Vulkanol. 14 (1931) 47–77.
A. Bonaccorso, S. Calvari, G. Garfì, L. Lodato, D. Patanè,
Dynamics of the December 2002 flank failure and tsunami at
Stromboli volcano inferred by volcanological and geophysical
observations, Geophys. Res. Lett. 30 (2003), doi:10.1029/
2003GL017702.
P. Tommasi, F.L. Chiocci, M. Marsella, M. Coltelli, M. Pompilio,
Preliminary analysis of the December 2002 instability phenomena
at Stromboli volcano, Abstract Volume from Meeting on
Occurrence and Mechanisms of Flow-Like Landslides in Natural
Slopes and Earthfills, Sorrento, Italy, 2004, pp. 297–303.
S. Tinti, G. Pagnoni, F. Zaniboni, Tsunami generation in
Stromboli Island and impact on the south-east Tyrrhenian coasts,
Nat. Hazards Earth Syst. Sci. 3 (2003) 299–309.
M. Ripepe, E. Marchetti, G. Ulivieri, A. Harris, J. Dehn, M.
Burton, T. Caltabiano, G. Salerno, Effusive to explosive
transition during the 2003 eruption of Stromboli Volcano,
Geol. Soc. Amer. Bull. 33 (2005) 341–344.
S. Calvari, L. Spampinatoi, L. Lodato, The 5 April vulcanian
paroxysmal explosion at Stromboli volcano (Italy) from field
observation and thermal data, J. Volcanol. Geotherm. Res. 149
(2006) 160–175.
M.L. Carapezza, S. Inguaggiato, L. Brusca, M. Longo,
Geochemical precursors of the activity of an open conduit
volcano: the Stromboli 2002–2003 eruptive events, Geophys.
Res. Lett. 31 (2004), doi:10.1029/2004GL019614.
A. Aiuppa, C. Federico, Anomalous magmatic degassing prior to
the 5th April 2003 paroxysm on Stromboli, Geophys. Res. Lett.
31 (2004), doi:10.1029/2004GL020458.
M. Mattia, M. Rossi, F. Guglielmino, M. Aloisi, Y. Bock, The
shallow plumbing system of Stromboli island imaged from 1 Hz
instantaneous GPS positions, Geophys. Res. Lett. 31 (2004),
doi:10.1029/2004GL021281.
M. Ripepe, E. Marchetti, P. Poggi, A. Harris, A. Fiaschi, G.
Ulivieri, Seismic, acoustic, and thermal network monitors the
2003 eruption of Stromboli Volcano, Eos, Trans.-Am. Geophys.
Union 85 (2004) 329–332.
A. Harris, D. Pirie, K. Horton, H. Garbeil, E. Pilger, H. Ramm, R.
Hoblitt, C. Thornber, M. Ripepe, E. Marchetti, P. Poggi,
DUCKS: low cost thermal monitoring units for near-vent
deployment, J. Volcanol. Geotherm. Res. 143 (2005),
doi:10.1016/j.jvolgeores.2004.12.007.