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Report on Etna (Italy) — July 1977

Natural Science Event Bulletin, vol. 2, no. 7 (July 1977)
Managing Editor: David Squires.

Etna (Italy) Lava effusion and explosive activity from a new vent

Please cite this report as:

Global Volcanism Program, 1977. Report on Etna (Italy). In: Squires, D. (ed.), Natural Science Event Bulletin, 2:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197707-211060.

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Etna

Italy

37.748°N, 14.999°E; summit elev. 3295 m

All times are local (unless otherwise noted)


Lava effusion and explosive activity, from a new vent at 3,200 m elevation just N of the Northeast Crater, began during the early morning of 16 July. A small lava lake, first observed at 0400, occupied the new vent, which was the source of two lava flows. The larger moved E into the Valle del Leone, and the smaller to the N. By 18 July, the flows had reached 2 km and 800 m length respectively. Strombolian activity began at 0515 on 16 July and rapidly increased in frequency and power. Ejecta reached 600 m in height and fell over an area ~1 km in diameter. The explosions had ended by 20 July and lava extrusion ended on 23 or 24 July.

Precision leveling two weeks before the eruption by John Guest and co-workers showed a 1-cm inflation of the S flank since September 1976, but strong deflation under aa fields on the N flank.

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.

Information Contacts: J. Guest, Univ. of London; R. Romano, and G. Frazzetta, IIV.