Report on Etna (Italy) — 19 May-25 May 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
19 May-25 May 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, 19 May-25 May 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 episodes of lava fountaining at Etna’s Southeast Crater (SEC) on 19 and 22 May that continued the recent pattern of Strombolian explosions followed by lava fountaining and lava flows. Strombolian activity began at 2340 on 19 May and produced ash plumes that drifted E. Activity intensified and lava fountains formed at 0234 on 20 May. At the same time lava overflowed the SEC and traveled SW, and within a few hours had reached 2,800 m elevation. The activity lasted about three and a half hours and then abruptly ended. The next episode during 0134-0454 on 22 May included Strombolian explosions and ash plumes that drifted SE; lava fountaining began at 0302 and flows traveled SW, overlapping the flows from 19 May. Explosions produced ash plumes that drifted SE around 0830 and 1014. Strombolian explosions intensified around 2031, producing dense ash plumes that drifted E. Lava fountains formed about two hours later, sending flows down the E and SW flanks; fountaining was over by 0038 on 23 May. A series of explosions were visible during 0351-0403, producing dense ash plumes that drifted E. Two ash plumes were observed rising from SEC’s E crater during the night and the day on 23 May. Intense explosive activity at SEC began at 1820 on 25 May, producing ash plumes that rose to 3.5 km (11,500 ft) a.s.l. and drifted E. Strombolian activity commenced at 1845 and lava fountains were visible around 2023. Lava flows were visible at 2244 and ash plumes drifted E at an altitude of 6 km (19,700 ft) a.s.l. Activity ceased by 0026 on 26 May.
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.