Report on Etna (Italy) — 10 March-16 March 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 10 March-16 March 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Etna (Italy). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 10 March-16 March 2004. 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, following the last eruption of Etna on 28 January 2003, no further eruptive activity had been observed as of 8 March 2004. Summit activity was limited to pulsating gas emissions from Northeast Crater and from one of the two vents within Bocca Nuova crater. The other central crater vents and Southeast Crater were essentially blocked, producing only extremely weak gas emissions. The first significant variation from this very low level of activity occurred between 12 and 14 February 2004, when a weak ash emission was observed within the summit crater plume. The high amount of juvenile components within the ash suggested an uprise of magma into the summit feeder conduit of the volcano, the first to occur since the end of the 2002-2003 flank eruption. Since January, several shallow earthquakes have been recorded at Pernicana fault on the volcano's NE flank.
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.