Report on Etna (Italy) — 17 July-23 July 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 July-23 July 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, 17 July-23 July 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 during 15-17 July sporadic explosions at Etna’s New Southeast Crater (NSEC) were accompanied by small ash puffs that quickly dissipated. Strombolian activity at NSEC increased during the morning of 18 July with explosions occurring at a rate of one every 1-2 minutes. In the following hours the rate of explosions increased, and by the evening Strombolian activity was almost continuous. The activity continued to intensify until 2300 when a sharp decrease occurred.
At 0009 on 19 July lava flowed from a new vent that opened on the lower NE flank of NSEC, and traveled towards the Valle del Leone. Within a few hours explosive activity again increased at NSEC; ash emissions occasionally rose from the Northeast Crater (NEC) and Bocca Nuova Crater. Explosive activity decreased and had ceased by noon. A sudden increase in explosive activity was recorded that afternoon and by the evening three vents within NSEC were producing Strombolian activity and sporadic ash emissions. Ashfall was reported in areas on the S flank. Explosive activity at NSEC again declined in the late evening. NEC produced abundant ash emissions until the morning of 20 July.
Just before 0800 on 20 July a new phase of explosive activity began at NSEC and lava effusion at the new vent on the NE flank increased. Later that morning explosive activity completely ceased; by evening the lava flow was only weakly fed.
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.