Report on Etna (Italy) — 6 November-12 November 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 November-12 November 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 6 November-12 November 2013. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3295 m
All times are local (unless otherwise noted)
INGV reported that ash emissions from Etna’s New Southeast Crater (NSEC) occurred at 1251 and 1254 on 6 November and were quickly dispersed by the wind. During 6-7 November several phases of frequent explosions produced ash puffs visible during the daytime and ejected incandescent material from Strombolian activity was visible at night. On 8 November the explosions occurred at intervals of several hours, producing small ash plumes that rose a few hundred meters above the summit and drifted ENE.
A culminating phase of lava fountains, ash emissions, and lava flows began at 0500 on 11 November, after about 10 hours of gradually intensifying Strombolian activity. Weather conditions prevented visual observations, but a strong increase in the volcanic tremor amplitude was detected. The phase of maximum intensity lasted about 7.5 hours, ending around 1130; the cessation of lava fountaining was followed by a long series of powerful explosions that generated loud bangs heard mostly in the N sector of the volcano. Ash and lapilli fell in areas E and NE. A voluminous lava flow expanded S from the NSEC, and two smaller lava flows traveled ESE and NE. Vigorous Strombolian activity continued, with explosions at intervals of 1-2 minutes, which launched incandescent material as high as 150 m above the crater rim. At night during 11-12 November Strombolian activity ceased and the lava flows were no longer active.
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.