Report on Etna (Italy) — 4 September-10 September 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 September-10 September 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Etna (Italy). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 4 September-10 September 2002. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
On 4 September the strong ash emissions that occurred at Etna's Northeast Crater the previous week were no longer observed, and only degassing occurred. Ash was emitted from Bocca Nuova crater once every 5-10 minutes and gas was emitted from Voragine and Southeast craters. On the night of 6 September, a M 5.6 earthquake, centered near the town of Palermo (~145 km NW of Etna) produced aftershocks that were felt in Catania (25 km SSE of Etna). On 8 September, strong Strombolian activity was observed at Northeast Crater. Explosions occurred every 1-3 minutes and incandescent material was ejected outside of the crater.
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.