Report on Etna (Italy) — 14 September-20 September 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 September-20 September 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 September-20 September 2011. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
Sezione di Catania - Osservatorio Etneo reported that the fourteenth eruption from Etna's New SE Crater in 2011 occurred during poor weather conditions on 19 September. Lava fountains rose from multiple vents within the crater and lava flows descended the W slope of the Valle del Bove. An ash plume drifted NE; ash and lapilli fell in an area to the N of Giarre (16 km E). The main phase of the event lasted from about 1020 until just after 1300. During the evening the lava flows were active and weak spattering continued from a vent at the SE base of the SE Crater cone.
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.