Report on Etna (Italy) — 11 December-17 December 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 December-17 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, 11 December-17 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)
According to an INGV-CT report, the eruption that began at Etna on 27 October continued through 13 December. On 8 December there was a sudden change in eruptive style. Strong Strombolian explosions from the 2,800-m vent replaced previous fire fountaining, signaling the end of ash emissions for about 24 hours. On 9 December fire fountaining resumed at this vent, but on the10th activity changed to Strombolian explosions. This alternating activity culminated on 10 December with the opening of two vents on the SSE base of the cone and the emission of two lava flows. These flows spread SW towards Monte Nero, and S towards the cinder cone that formed at 2,550-m elevation during the 2001 eruption (also called Laghetto cone).
The S flow expanded on the 11th and 12th, and as of the 13th it had reached 300 m from the road leading to the Rifugio Sapienza tourist area, about 3.3 km from the vent. Civil Protection authorities, for the second time during this eruption, built an earth dam to divert the lava away from Rifugio Sapienza structures. SO2 emission rates significantly decreased on 1 December, dropping from previous estimates of ~20,000 to ~7,000 tons/day.
According to a Reuters news article, a lava flow that reached the Rifugio Sapienza tourist area on the evening of 16 December caused an explosion that destroyed a building and injured 32 people. The article stated that the exact cause of the explosion was unknown.
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.