Report on Etna (Italy) — 24 December-30 December 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 December-30 December 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, 24 December-30 December 2002. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
INGV-CT reported that the eruption that began at Etna on 27 October continued through 23 December. Lava flows and Strombolian activity occurred at the volcano's S flank at the 2,750 m vent. During 9-10 December, two vents opened at the SE base of the 2,750-m cinder cone that fed four major lava flows which spread between the S and SE. On the 17th a strong explosion occurred at a building in the Rifugio Sapienza tourist area. The explosion was not directly caused by the eruption, but by the vaporization of oil or water, still contained inside the building, when the lava flow contacted it.
The effusion rate from the two vents gradually decreased, eventually causing the closure of the western vent and then the lack of supply to the lava flows spreading SW towards Monte Nero. A new vent opened on 17 December at the S base of the 2,750 m cinder cone, a few meters W of the previous vents. A lava flow soon started from this vent, spreading SW towards Monte Nero. Lava flows from the 17 December vent slowed down and crusted over on 22 December, when a new vent opened at the SW base of the 2,750 m cinder cone. Again, a flow traveled SW towards Monte Nero. As of 23 December the lava flow continued to flow in this direction. SO2 emission rates remained relatively low, around 7,000 tons per day. Updated maps of the lava flows, and reports of the eruptive activity, gas emission, and ash composition can be found on the INGV-CT web page (in Italian).
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.