Report on Stromboli (Italy) — November 1990

Bulletin of the Global Volcanism Network, vol. 15, no. 11 (November 1990)
Managing Editor: Lindsay McClelland.

Stromboli (Italy) Vigorous tephra ejection and lava fountaining from summit vents

Please cite this report as:

Global Volcanism Program, 1990. Report on Stromboli (Italy). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:11. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199011-211040.

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Stromboli

Italy

38.789°N, 15.213°E; summit elev. 924 m

All times are local (unless otherwise noted)


Although the eruption was apparently somewhat less vigorous in late October, activity observed by Boris Behncke on 7-8 November was stronger than during his previous visits in September 1989 and March-April 1990. Vigorous gas emission fed a dense plume that obscured the vent area during the day, but visibility improved after sunset and a clear view of the craters was possible after 2000 on 7 November. Although vent morphology had changed somewhat, vent configuration was much the same as in April.

The main focus of activity was a cluster of at least four vents in C1 (at the NE end of the summit crater group) that were almost continuously erupting. Intense bomb and spatter ejection started at 1717 on 7 November and continued for at least 2 hours, with loud roaring like a jet aircraft. The strongest eruptions occurred from C1's easternmost vent (1), site of nearly continuous bomb ejections in early October. On 7 November, vent 1 ejected lava fountains to 100 m height, often followed within seconds by eruptions from vent 3, the southernmost vent in C1. Individual bursts of spatter, mostly from vent 3, were accompanied by loud explosions; gas had been emitted from this vent nearly once a second in early October. Between stronger bursts, very small lava fountains were continuously active within vents 2 and 3. Spatter was ejected to ~20 m height every 10-20 seconds from vent 3 and another vent to the NE. At 0100 on 8 November, fountains rose 40-50 m from the latter vent, and loud roaring was continuing. None of the vents produced ash plumes after 1800 on 7 November. The former vent at the NE end of C1 had apparently ceased erupting and may have been buried by the growing cone at vent 1, a prominent feature that had been too small to be visible from the summit in April.

Eruptive episodes from C3 (at the SW end of the summit crater group) occurred about twice an hour, producing lava fountains that rose as much as 100 m, and sometimes diffuse brown ash plumes and light tephra falls onto the summit platform. Most episodes consisted of several pulses of fountaining over a period of ~30 seconds. A strong eruptive episode at 1710 on 7 November was followed by bursts of spatter at intervals of 10-20 seconds until 1717. Another particularly violent burst at 2000 covered most of the crater area with glowing bombs and spatter. An area of 3 pits in C3 that had contained actively degassing lava in April was occupied by two small (<1 m diameter) vents that emitted low fountains of spatter. Much of C3 had been filled with recent pyroclastics.

Geologic Background. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small, 924-m-high island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period from about 13,000 to 5000 years ago was followed by formation of the modern Stromboli edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

Information Contacts: B. Behncke, Ruhr Univ, Germany.