Report on Etna (Italy) — 31 July-6 August 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 July-6 August 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 31 July-6 August 2019. 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 on 25 July Etna’s New Southeast Crater (NSEC) periodically emitted gas and ash. At 0630 on 27 July the seismic network detected a sudden increase in tremor amplitude, and at 0915 a new fissure opened on the S flank of NSEC. Explosive activity at the crater intensified at 1020 and a dense, ash-rich plume rose to 4.5-5 km a.s.l. and drifted E. A thin layer of ash was deposited in Giarre, Riposto and Torre Archirafi. Lava emerged from the S part of the new fissure and traveled SW and S; by 1235 the longest part of the flow had reached 2,850 m elevation and by 1330 it had reached 2,600 m elevation. Beginning at 1321 a sequence of particularly strong explosions generated ash plumes that rose as high as 7.5 km a.s.l. Explosive activity decreased around 0440 on 28 July, and lava effused from the vent at a lower rate. Starting at 0846 the Northeast Crater (NEC) occasionally emitted small plumes of red-brown ash. Explosive and effusive activity at NSEC ceased that evening. Activity during 29 July-4 August consisted of a few episodes of ash emissions at Bocca Nuova Crater and NEC.
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.