Report on Stromboli (Italy) — January 2003
Bulletin of the Global Volcanism Network, vol. 28, no. 1 (January 2003)
Managing Editor: Edward Venzke.
Stromboli (Italy) Lava emissions continue into January; crater morphology changes
Please cite this report as:
Global Volcanism Program, 2003. Report on Stromboli (Italy). In: Venzke, E (ed.), Bulletin of the Global Volcanism Network, 28:1. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200301-211040.
38.789°N, 15.213°E; summit elev. 924 m
All times are local (unless otherwise noted)
The effusive eruption at Stromboli, which began 28 December 2002, continued into January 2003. Effusion of lava occurred at a main vent located at 500 m elevation in the middle of the Sciara del Fuoco, within the scar remaining after the 30 December 2002 landslide. The position of this vent has been rather stable since its opening, also on 30 December. Another vent, located at 600 m elevation at the NE base of Crater 1, has been active several times during the eruption, forming low-effusion rate, short lava flows lasting from a few hours to a few days. Effusion rates along the Sciara del Fuoco from the 500 m vent were very variable. During peaks in effusion rate, aa lava flows were reaching the sea causing phreatic explosions at the front. A decrease in effusion rate formed a fan of thin, narrow lava flows spreading on the upper flow field without reaching the sea.
Activation of the 600 m vent occurred each time the 500 m vent showed a marked decrease in effusion rate, suggesting a temporary magma level rise within the feeder conduit of the volcano. This observation was confirmed by an approximately 50°C increase in temperature at the bottom of the craters during activation of the 600 m vent, recorded during daily thermal mapping from a helicopter.
Lava flow emission along the Sciara del Fuoco formed a very thick flow field within the landslide scar of 30 December. Occasional small landslides from the unstable walls of the Sciara cover the lava flows with talus, increasing the thickness and instability of the flow field.
During a helicopter-borne thermal survey carried out on 12 January, arcuate cracks were detected around the southern base of the summit craters of the volcano. Other fractures, oriented NE-SW, cut through the craters. These probably result from drainage of magma in the upper part of the conduit. Collapse of the crater floor in early January significantly changed the morphology of the upper part of the volcano. Crater 2 (the middle crater) has disappeared, and Crater 1 (NE) and Crater 3 (SW) were joined together to form a unique, elongate depression. No explosive activity has been detected at the summit craters of the volcano since the start of the effusion within the Sciara del Fuoco.
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: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Catania Piazza Roma 2, 95123 Catania (URL: http://www.ct.ingv.it/, Email: email@example.com).