Report on Stromboli (Italy) — 11 November-17 November 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 November-17 November 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Stromboli (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 November-17 November 2020. Smithsonian Institution and US Geological Survey.
38.789°N, 15.213°E; summit elev. 924 m
All times are local (unless otherwise noted)
INGV reported that during 9-15 November activity at Stromboli was characterized by ongoing explosive activity from Area N (North Crater area) and in Area C-S (South-Central Crater area). Explosions from the N1 vent (Area N) ejected lapilli and bombs 80-250 m high, and produced ash emissions. Explosions at three N2 vents (Area N) ejected a mix of coarse and fine material at a rate of 6-10 events per hour. Explosions from vents in Area C-S also ejected fine material 150 m high at a rate of 1-2 events per hour.
A series of at least four explosions began at 2104 on 10 November with a major, six-minute-long explosion in the southern part of Area C-S. The event ejected pyroclastic material which fell radially and along the Sciara del Fuoco, and produced a vertical ash plume. Within 30 seconds a second pulse of activity from the central crater area ejected coarse material 300 m above the vent and then produced in tense lava fountaining. A small explosion from vent N2 concluded the series. During an overflight the next day, scientists identified thermal anomalies from lava at the bottom of the S1 and C craters (central part of crater terrace) and craters N1 and N2. A small lava flow from S1 was also visible, and a small hornito (h1) had formed just outside the crater. A second hornito (h2) had formed on the south flank of N2.
A series of major explosive and landslide events began at 1017 on 16 November and lasted for four minutes (based on the seismic signals). Explosions produced a dense ash cloud that rose 1 km, and within minutes caused ash and lapilli to fall in the town of Stromboli, about 2 km away on the NE coast of the island. A pyroclastic flow rapidly descended the Sciara del Fuoco to the NW coastline and expanded 200 m over the sea surface.
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 took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to 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.