Report on Etna (Italy) — 13 November-19 November 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 November-19 November 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, 13 November-19 November 2002. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
The eruption that began at Etna on 27 October continued through 12 November. INGV-CT reported that on 12 November at 1340 volcanic tremor recorded by their seismic network gradually increased, reaching an amplitude two times higher than before. This seismicity increase occurred when fire fountaining and ash emission from the vent at 2,750 m elevation on the volcano's S flank suddenly stopped and were substituted by Strombolian activity. This change marked an increase in the magma level within the conduit, and on the 13th at 1600 a lava flow was emitted from the S base of the upper cinder cone that formed around the 2,750-m vent. The lava flow spread S, filling up the intermediate and lower cinder cones along the same eruptive fissure. It expanded SW towards Monte Nero, running parallel to the lava flow that had stopped on 31 October. By 14 November at 0930 the lava-flow front had reached 1.2 km in length, was at an elevation of 2,450 m a.s.l., and traveled at a velocity of about 2-3 m per minute. Strombolian activity was substituted by fire fountaining and the emission of ash that reached 3.5 km a.s.l. and drifted N and E. SO2 emission from Etna remained very high and fluctuated around 20,000 tons per day. According to a news article, Fontanarossa Airport in Catania, which had been closed since 10 November, reopened on the 13th. The Toulouse VAAC reported that moderate-to-severe ash emissions had occurred at Etna since the eruption began, but had become weaker since the afternoon of 12 November.
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.