Report on Etna (Italy) — 6 September-12 September 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 September-12 September 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 6 September-12 September 2006. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
On 14 July, a fissure opened on the E flank of the SE Crater of Etna and produced a lava flow that traveled E to the Valle del Bove. Moderate Strombolian activity from the E flank of the SE Crater produced a small amount of ashfall on Catania (~25 km SSE of the volcano). The lava flow reached a maximum distance of 3 km within the Valle del Bove and ceased on 24 July. On 26 July, strong explosions were heard from the rim of the NE crater.
On 31 August, Strombolian activity from the summit of the SE Crater produced lapilli and bombs that fell mainly in the crater. The ejecta filled the crater and overflowed on the E side on 5 September, forming lava falls that accumulated in a steep-sided circular depression on the middle part of the E flank. On 7 September, the sluggish a'a' flow breached the E rim and spread out on the E flank of the SE Crater and towards the Valle del Bove rim. Explosive activity at the SE Crater summit produced lava blocks that fell to the base of the cone.
On 10 September, a rockfall from a wall that divided the SE Crater and the depression on the middle part of the E flank produced an ash plume that drifted W. Lava flows and Strombolian activity from the summit of the SE Crater continued on 11 September.
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.