Report on Stromboli (Italy) — 20 August-26 August 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 August-26 August 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Stromboli (Italy). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 20 August-26 August 2003. Smithsonian Institution and US Geological Survey.
38.789°N, 15.213°E; summit elev. 924 m
All times are local (unless otherwise noted)
INGV-CT reported that after the effusive eruption at Stromboli ceased between 21 and 22 July, explosive Strombolian activity became more common at both summit craters. Four active vents were observed within Crater 1 (the NE crater), and one funnel-shaped incandescent depression was seen within Crater 3 (the SW crater). Strombolian activity during the first half of August was very intense at Crater 1, with spattering that led to the creation of a spatter cone on the crater floor and fallout of incandescent bombs on the cone's outer flanks. Explosive activity at Crater 3 appeared to be deeper than at Crater 1 and was often accompanied by ash emission. During the first half of August thermal images of the apparently inactive flow field revealed a thermal signature within cracks on the upper flow field and within skylights along two lava tubes in the upper Sciara del Fuoco, at about 550 m elevation. Temperatures over 300°C and incandescence at these hot spots suggest endogenous growth of the apparently inactive lava flow field. Incandescence and thermal signatures at these sites were not seen between 22 and 31 July.
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 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 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.