Report on Fagradalsfjall (Iceland) — 21 April-27 April 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
21 April-27 April 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, 21 April-27 April 2021. Smithsonian Institution and US Geological Survey.
63.895°N, 22.258°W; summit elev. 250 m
All times are local (unless otherwise noted)
IMO reported that the fissure eruption in the W part of the Krýsuvík-Trölladyngja volcanic system, close to Fagradalsfjall on the Reykjanes Peninsula, continued during 21-27 April. A M 4.1 earthquake was recorded at 2305 on 21 April about 6 km WSW of the fissures and followed by several aftershocks; it was the largest on the Reykjanes Peninsula since 15 March, before the eruption began. The average lava-flow rate was calculated by the University of Iceland’s Institute of Earth Sciences using photographs most recently collected during an overflight on 26 April. They reported that during the previous five days the flow rate from all of the active craters averaged just over 6 cubic meters per second; the average rate during the 38 days of the eruption was 5.6 cubic meters per second. The area of the flow field was 1.13 square kilometers, the total volume was over 18.4 million cubic meters, with an average thickness of just over 16 m. The Aviation Color Code remained at Orange due to the lack of ash and tephra emissions.
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.