Report on Etna (Italy) — 30 October-5 November 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 October-5 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, 30 October-5 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)
Volcanic and seismic activity continued at Etna during 29 October to 4 November after a new eruption commenced on 27 October. The eruption consisted of fissures opening on the volcano's S and N flanks, lava emission from these fissures, and fire fountains rising several hundreds of meters. Significant ash emissions led to the closure of Fontanarossa airport and produced ash clouds that drifted as far as Libya. According to an INGV-CT report, two major lava flows were emitted from the lower end of the northern fissure and spread toward the NE and E. The NE flow stopped on 31 October after traveling 2 km, when a decline in effusion rate was observed. As of 1 November the E flow had slowed down, but it was still moving and crusting over in the middle portion of the flow field. A few sectors of solid crust were detected during a survey with the helicopter of the Civil Protection using a thermal camera. This suggests that a lava tube is forming on this lava flow. The lava flow from the S fissure started about 12 hours after the N one, spread SW, and split in two branches around Monte Nero, following the same path as one of the 2001 eruption's lava branches. The S flows stopped on 31 October, reaching a total length of about 1 km. Fire fountains and phreatomagmatic activity decreased in intensity with time at both the N and S fissures. As of 1 November the effusion rate from the N fissure was declining, which increased the possibility of lava-tube formation along the E flow.
According to the Toulouse VAAC, ash was emitted from Etna during the report period and was occasionally visible on satellite imagery rising to 6.1 km a.s.l. On 1 November ash was visible on satellite imagery extending ENE from Etna's summit, reaching the coast of Greece. On several occasions meteorological clouds in the vicinity of Etna prohibited satellite views, but the Etna web video camera located in Catania showed continuous ash emission on 4 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.