With a potentially very large eruption from this system looming, now is a good time to review the “fires” — a term used locally for any series of eruptions from a given volcanic system on this unusual hybrid of Mid-Atlantic Ridge and mantle plume.
It’s a complex place (mild jargon alert).
I couldn’t find a video that adequately covers the eruptions thus far. Instead, let’s go with a combination of Global Volcanism Program reports and a few selected videos. (This is only hitting the high spots — the GVP weekly and bulletin reports will give the detailed view.)
Geldingadalir
Uploaded March 28, 2021.
Global Volcanism Program, May 2021:
The Krýsuvík-Trölladyngja system, one of five volcanic systems along the Reykjanes Peninsula in Iceland, is characterized by a 50-km-long composite fissure swarm trending about N38°E. The system includes the shorter Fagradalsfjall and Krýsuvík fissure swarms; there is no clear sign of a central volcano. Seismicity in this area began on 24 February 2021 and continued to increase through March, causing some surface fractures. An orange glow observed on 19 March indicated the start of a fissure eruption near Fagradalsfjall in the Geldingadalur (also referred to as Geldingadalir) valley (figure 1). Several fissure vents opened along a NE-SW trend, accompanied by white gas-and-steam emissions, spatter, and lava fountains; flows began to fill Geldingadalur and eventually reached the Meradalir valley…” Read more
And this happened spontaneously:
The activity continued all summer and into the fall.
Then the eruption ceased; soon afterward, experts reported a new round of ground inflation.
Fagradalsfjall: Meradalir
Global Volcanism Program, late December 2021:
“…Seismicity increased at 1800 on 21 December in an area 2-4 km NE of Geldingadalir. The seismicity notably intensified at 0030 on 22 December with 1-10 earthquakes recorded per minute, bringing the total number of events to about 900 by 0222. The largest event was a M 3.3. The Aviation Color Code was raised to Orange.
Geological Summary. Although the Fagradalsfjall fissure swarm has previously been considered a split or secondary swarm of the Krýsuvík–Trölladyngja volcanic system, as of September 2022 Icelandic volcanologists managing the Catalogue of Icelandic Volcanoes made the decision to identify it 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.”
Uploaded August 4, 2022.
Global Volcanism Program, September 2022:
“…An effusive fissure eruption began around 1315 on 3 August near the border of the previous lava flow field N of Fagradalsfjall in Meradalir. IMO scientists, in conjunction with the Coast Guard, took photos of the activity during a surveillance flight and made measurements of the fissure that appeared at the northern edge of the lava field from the last eruption; initial measurements showed that the fissure was about 300 m long (figures 27 and 28). Webcam video showed lava fountains rising along the fissure, causing IMO to increase the ACC to Orange at 1536. Gas-and-steam plumes rose 500-1,000 m high, but no ash was detected. Lava flows were reported traveling downslope to the NW. The flow rate was about 32 m3/s during the initial hours of the eruption, which then…” Read more
Fagradalsfjall: Litli Hrutur
Global Volcanism Program, July through August 2023:
“According to the Institute of Earth Sciences lava continues to eruption from main vent at Fagradalsfjall and travel S and SW. On 14 July the advancing edge of the flow connected with the 2021 lava field in the NE part of Meradalir . The main vent was elongated and about 22 m tall on 15 July. During 13-17 July the lava flow rate was an estimated 12.7 cubic meters per second, and by 18 July the total erupted volume was about 8.4 million cubic meters. The flow advanced an average of 300-400 m per day, though the distance was highly variable. Flow thicknesses averaged 10 m, though some areas reached 20 m…
…
“At 1706 on 5 August IMO lowered the Aviation Color Code for Fagradalsfjall to Yellow (the second level on a four-color scale), noting that the eruption had declined during the previous few days and very minor activity at the crater was visible in webcam images. Tremor had decreased during the previous 36 hours and reached background levels by 1500 on 5 August. Gas plumes had typically risen 1-2 km above the vent, though on 1 August plumes rose more than 2.5 km, and according to news articles, a notable amount of fume rose from the vent on 4 August. The crater had become deeper and smaller by 4 August. Activity was last seen on 5 August and a thermal anomaly in the crater was last identified in satellite images on 6 August…” Read more (Activity weekly reports as of August 2023.)
Edited November 15, 2023, at 0022 UTC.
Lagniappe:
Featured image: Juraj Kamenicky/Shutterstock, taken July 14, 2021, at Geldingadalir.
Flight To Wonder 