Report on Reykjanes (Iceland) — 1 November-7 November 2023
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 1 November-7 November 2023
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2023. Report on Reykjanes (Iceland) (Sennert, S, ed.). Weekly Volcanic Activity Report, 1 November-7 November 2023. Smithsonian Institution and US Geological Survey.
63.817°N, 22.717°W; summit elev. 140 m
All times are local (unless otherwise noted)
IMO reported that increased seismicity and deformation at the Reykjanes Peninsula were ongoing during 1-7 November and indicated magma accumulation at depths of 4-5 km in an area NW of Mt. Thorbjorn. A total of 7 cm of uplift was recorded in satellite data and by the Global Navigation Satellite System (GNSS) station near Mt. Thorbjorn during 27 October-6 November. The rate of inflation was fairly constant though it began to accelerate on 3 November. Data models indicated that the volume change associated with the uplift was double that of the four previous inflation events recorded during 2020-2022; the inflow of magma was estimated at 7 cubic meters per second, or four times greater than the highest inflow rate recorded during the previous events.
Intense seismicity continued. Over 10,500 earthquakes were detected during 25 October-1 November, out of which more than 26 exceeded M 3 and the largest was a M 4.5 recorded at 0818 on 25 October. Seismicity increased for early on 3 November, and then notably decreased around 1730. The signals were located along previously known faults, aligned in a N-S direction W of Mt. Thorbjorn. There was no indication of magma migrating to the surface. During 4-7 November there were around 2,200 earthquakes, which were located between Mt. Thorbjorn and Sýlingafell during 6-7 November.
Geological Summary. The Reykjanes volcanic system at the SW tip of the Reykjanes Peninsula, where the Mid-Atlantic Ridge rises above sea level, comprises a broad area of postglacial basaltic crater rows and small shield volcanoes. The submarine Reykjaneshryggur volcanic system is contiguous with and is considered part of the Reykjanes volcanic system, which is the westernmost of a series of four closely-spaced en-echelon fissure systems that extend diagonally across the Reykjanes Peninsula. Most of the subaerial part of the system (also known as the Reykjanes/Svartsengi volcanic system) is covered by Holocene lavas. Subaerial eruptions have occurred in historical time during the 13th century at several locations on the NE-SW-trending fissure system, and numerous submarine eruptions dating back to the 12th century have been observed during historical time, some of which have formed ephemeral islands. Basaltic rocks of probable Holocene age have been recovered during dredging operations, and tephra deposits from earlier Holocene eruptions are preserved on the nearby Reykjanes Peninsula.