Report on Etna (Italy) — 22 August-28 August 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 August-28 August 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 August-28 August 2007. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3320 m
All times are local (unless otherwise noted)
On 15 August, the South East Crater at the summit of Etna produced ash emissions from a depression on the E flank. A resultant ash plume rose a few tens of meters and quickly dispersed. Ashfall formed a red deposit on the flanks of the South East Crater cone. Based on observations using the summit web camera, incandescent blocks associated with energetic emissions of ash were propelled out of the depression on 21 August. A field assessment on 22 August revealed that the ash emissions were associated with collapses within the depression. During 23-24 August, the ash emissions increased in frequency and erupted incandescent blocks were again observed.
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.