Report on Fagradalsfjall (Iceland) — 3 March-9 March 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
3 March-9 March 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, 3 March-9 March 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 seismicity in the area between the Krýsuvík and Reykjanes-Svartsengi volcanic systems remained elevated during 4-10 March. GPS and InSAR data indicated that the intrusion was ongoing, with magma moving slowly SW along a fault between Keilir and Fagradalsfjall at depths of 2-6 km. Seismicity fluctuated during 6-7 March but continued to be elevated; the largest event was a M 5.1 on 7 March. The geophysical and satellite data on 8 March suggested that magma movement had decelerated over the past week, and was possibly as shallow as 1 km. A burst of seismicity was recorded around 0520 on 9 March, concentrated at the S end of the intrusion in an area that was most likely source of the magma. On 10 March IMO stated that more than 34,000 earthquakes had been detected during the past two weeks, a total larger than all of 2020 which was characterized as an unusually high year for seismicity. The Aviation Color Code for Krýsuvík remained at Orange.
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.