Report on Etna (Italy) — 11 May-17 May 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 May-17 May 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 May-17 May 2011. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
Sezione di Catania - Osservatorio Etneo reported that on 8 May mild and discontinuous Strombolian activity resumed at the pit crater located on the E flank of Etna's SE Crater cone. On 11 May volcanic tremor amplitude progressively increased, and at about 2030 lava started to overflow the E crater rim. The activity intensified during the following hours and, shortly before 0400 on 12 May, culminated with lava fountaining which generated an ash cloud that drifted SSE. The lava fountaining lasted around 2 hours, showing a gradual diminution around 0545; an abrupt drop in the volcanic tremor amplitude at 0610 marked the end of the eruptive activity.
Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.