Report on Fagradalsfjall (Iceland) — 24 February-2 March 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
24 February-2 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, 24 February-2 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 Krýsuvík and Reykjanes-Svartsengi volcanic systems remained elevated during 26 February-1 March. More than 6,000 earthquakes had been detected after a M 5.7 event was recorded at 1005 on 24 February; two of those events were above M 5. The earthquakes were distributed over a 25-km-long section of a N-S striking fault along the E-W striking plate boundary, primarily located between Keilir and Fagradalsfjall. GPS data showed 4 cm of horizontal displacement near the epicenter of the M 5.7 event. An InSAR interferogram showed left-lateral movement over a large section of the plate boundary. Tremor began to be recorded by several stations at 1425 on 3 March, in an area located 2 km SW of Keilir. The signals possibly indicated magma rising towards the surface and prompted IMO to raise the Aviation Color Code for Krýsuvík to 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.