Report on Fagradalsfjall (Iceland) — 25 August-31 August 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
25 August-31 August 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Fagradalsfjall (Iceland). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 August-31 August 2021. Smithsonian Institution and US Geological Survey.
63.895°N, 22.258°W; summit elev. 250 m
All times are local (unless otherwise noted)
The fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 25-31 August, though weather often obscured the view of the vents. Low lava fountaining and overflows from the main vent were interspersed with periods of calm. Parts of the crater sometimes collapsed and produced minor ash clouds based on webcam views. According to a news article, lava flowed into the S part of Meradalir valley and then down a hillside into Nàtthagi valley on 26 August in multiple branches. Observers noted that parts of the flows were turbulent and splashed above the flow surface. Lava stopped advancing at around 1600 as the eruption paused. A geophysicist noted that lava had been flowing S more often due to the new vent that had opened on the flank of the cone during the previous few weeks. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions, though IMO warned of the potential for lapilli and scoria fallout within a 650 m radius of the active vent. Authorities also warned of gas emission hazards.
Geological Summary. Although the Fagradalsfjall fissure swarm has previously been considered a split or secondary swarm of the Krýsuvík–Trölladyngja volcanic system (https://volcano.si.edu/volcano.cfm?vn=371030), as of September 2022 Icelandic volcanologists managing the Catalogue of Icelandic Volcanoes (https://icelandicvolcanoes.is/) made the decision to identify Fagradalsfjall as a distinct separate system. The recent eruptions and related reports have been reassigned here, and other content will be prepared and adjusted as appropriate in the next few months.