Report on Etna (Italy) — 3 February-9 February 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 3 February-9 February 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, 3 February-9 February 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 that Strombolian activity from all four of Etna’s summit craters, the Southeast Crater (SEC), the Northeast Crater (NEC), Bocca Nuova (BN), and Voragine (VOR), was visible during 1-7 February; the last time that had occurred was during 1998-1999. The strongest and almost continuous Strombolian explosions at SEC originated from two vents in the E part of the top of the cone. Tephra accumulated near the top of the cone and rolled down the flanks. Minor ash emissions rapidly dispersed. Less-intense Strombolian activity occurred at the S vent. Intra-crater Strombolian activity at NEC sometimes produced nighttime crater incandescence. Strombolian activity at BN sometimes ejected coarse material beyond the crater rim, and rare ash emissions that had diffuse ash content. On 5 February scientists observed explosions from three vents at the bottom of the crater that had formed cinder cones. Nearby was another cone that occasionally produced dense emissions that rapidly dispersed. Strombolian activity at VOR ejected material that sometimes rose above the crater rim and generated diffuse ash emissions. On 5 February lava flowed into BN, overlapping flows from the previous week.
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.