Report on Etna (Italy) — 7 January-13 January 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 January-13 January 2015
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, 7 January-13 January 2015. 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 at night during 6-7 January the frequency of Strombolian explosions at Etna's Voragine Crater decreased; however, some of the explosions ejected incandescent pyroclastic material outside of the crater and onto the W and SW flanks. On 7 January many of the small explosions generated brown ash plumes that rose a few hundred meters above Etna's summit and quickly dissipated. Strombolian activity increased on 8 January, possibly from two vents within the crater. Pyroclastic material continued to be ejected out of the crater. Early on 9 January Strombolian activity again decreased and gave way to ash emissions that rose several hundred meters. Ash emissions continued the next morning, decreased, and had almost completely ceased by late morning. Ash emissions resumed in the afternoon and were sometimes accompanied by Strombolian explosions. Ash emissions on 13 January were continuous in the morning but then decreased in frequency by the afternoon.
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.