Report on Etna (Italy) — 4 August-10 August 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
4 August-10 August 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Etna (Italy). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 4 August-10 August 2021. Smithsonian Institution and US Geological Survey.
37.748°N, 14.999°E; summit elev. 3320 m
All times are local (unless otherwise noted)
INGV reported continuing activity at Etna’s summit craters during 2-8 August, mainly from the Northeast Crater (NEC) and the Southeast Crater (SEC). Gas emissions rose from Voragine Crater and from two active craters in Bocca Nuova. A series of discontinuous ash emissions from NEC began at 1350 on 4 August and lasted about two hours. An ash plume rose to 1.8 km (6,000 ft) a.s.l. and drifted NE. Similar but less intense ash emissions were visible on 5 August. The reddish mostly fine-grained material emitted from NEC was erupted when no thermal anomalies were present in the crater, suggesting that they were the result of landslides rather than eruptive activity. Strombolian activity began at SEC at 2057 on 7 August and was characterized by isolated explosions and the ejection of incandescent material beyond the crater rim; activity ceased during the night. An explosion at 2056 on 8 August was followed by the resumption of Strombolian activity at 0030 on 9 August. Incandescent material was again ejected beyond the crater rim and an ash plume drifted SE.
Geological Summary. 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.