Report on Etna (Italy) — 13 May-19 May 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 May-19 May 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, 13 May-19 May 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 the new episode at Etna’s New Southeast Crater (NSEC) that began on 12 May continued the next day. At 0410 on 13 May a series of small collapses accompanied the opening of three vents, along a fracture oriented E-W, below the E rim of NSEC, one of which effused a small lava flow. At 0800 a fracture at the vent propagated 200 m from the rim down the cone within 10 minutes. This event was accompanied by collapses, along with reddish ash ejection onto the summit area and the high S flank. Strombolian activity increased that night and was characterized by almost continuous Strombolian explosions, sometimes accompanied by ash emissions. This activity continued during 14-15 May. Ash plumes rose a few hundred meters and dispersed with the wind; minor ashfall was reported in areas from the S to the NE. A single lava flow traveled NE towards Mt. Rittman, and then E towards Mt. Simone where it formed two branches. One branch approached the base of the N wall of the Valle del Bove while the other traveled W to a distance 5 km from NSEC. Activity decreased on 15 May and ceased on 16 May.
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.