Report on Etna (Italy) — 30 December-5 January 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 December-5 January 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 December-5 January 2016. 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 after intense activity at Etna's Voragine Crater, Bocca Nuova, and the New Southeast Crater (NSEC) during the first 10 days of December, activity shifted to the Northeast Crater (NEC). During 9-10 December Strombolian activity was detected at NEC, with a few ejected incandescence bombs falling onto the outer flank and abundant ash emissions. Activity gradually diminished over a few days. On 13 December ash emissions rose from NSEC and on 18 December the Voragine Crater produced two brief ash emissions. Ash emissions began at 1100 on 28 December from a vent located high on the E flank of the NSEC cone. The emissions ceased in the afternoon; very minor and sporadic explosions continued from the same vent during the following days.
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.