On Monday 11. September 2023 an earthquake swarm took place close to Geirfugladrangur island out on the Reykjanes ridge. Largest earthquake had a magnitude of Mw3,4. Other large earthquake had magnitude of Mw3,2 and Mw3,0. Other earthquakes where smaller in magnitude, according to Icelandic Met Office, but this earthquake swarm has not been reviewed yet so magnitudes might change when that happens.
Earthquake swarm on the Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.
Earthquakes in this earthquake swarm where not felt, because of distance from the coastline and populated areas.
During the night of 9. September 2023 an earthquake swarm started at 03:24 UTC with a magnitude Mw3,8 earthquake. This earthquake was felt in Reykjavík area and other nearby areas.
Green star in Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met office.
Its unclear if this earthquake swarm is ongoing. There is a lot of earthquake activity in this area because of inflation in Fagradalsfjall volcano.
Today (7. September 2023) an tyke intrusion took place in Fagradalsfjall volcano. The main depth of the dyke intrusion is at around 7 km depth. All earthquakes following this dyke intrusion where small in magnitude, from Mw0,1 in magnitude and up to Mw1,0 in magnitude. This seems to be a rather large dyke intrusion, since part of it does not create any earthquake activity at all because of earlier dyke intrusions at this depth in this part of Fagradalsfjall mountain.
Earthquake activity in Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.
Morgunblaðið (link below) is reporting that inflation has now reached 15mm in this area. This is really soon after the end of the eruption, since in last three eruptions, dyke intrusions and other early signs of activity that an eruption is about to happen starts around three to six months earlier before an eruption happens at the ten month time, as has been the case in the last three eruptions. It is possible that next eruption is going to happen earlier than last three eruptions. It is possible to know when next eruption is going to happen.
Today (1. September 2023) at 17:55 UTC an earthquake with the magnitude of Mw3,1 took place in Reykjanes volcano. This earthquake was located out in the ocean and some distance from the coastline. I don’t think it was felt. Few other smaller earthquakes took place at the same location following the largest earthquake.
Earthquake activity in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.
There is a storm now in this area of Iceland. That makes detection of smaller earthquakes impossible, along with distance from the coastline. If this earthquake swarm is going to be ongoing when the storm ends is impossible to know.
During the night of 26. August 2023 an dyke intrusion started in Brennisteinsfjöll volcano. This was in the form of many small earthquakes, most of them did not reach magnitude Mw1,0. What gives this away as an dyke intrusion is the fact the deepest earthquake in this swarm had a depth of 21,1 km. There was interestingly, a lot of surface earthquakes. I am not sure on why that is.
Earthquake activity in Brennisteinsfjöll volcano. Copyright of this image belongs to Icelandic Met Office.
There’s no risk of eruption at the moment from Brennisteinsfjöll volcano. Earthquake activity is too low and this process is clearly not far along now for an eruption too happen. That might change without much warning at some point.
Yesterday (13. August 2023) an large earthquake swarm took place close to Geirfugladrangur (small rock island, population birds) on the Reykjanes ridge. The largest earthquake had a magnitude of Mw4,5 and was felt to Akranes town and possibly in other nearby towns on Reykjanes peninsula. There where not many reports about this earthquake being felt. Something above 400 earthquakes took place during the most active phase of this earthquake swarm.
Earthquake activity on the Reykjanes ridge. Copyright of this image belongs to Icelandic Met Office.
This earthquake swarm seems to be ongoing. It is at the moment, at much slower rate than before. There are clues that suggest this might have been a earthquake activity connected to magma movements in this area. Its difficult to be sure, because this area is under the ocean and measuring what is going on gets more difficult as future away from land activity happens. Eruption at this distance is going to appear on the Icelandic Met Office SIL network.
Today (30. July 2023) an earthquake swarm took place in Torfajökull volcano. This volcano is located north of Katla volcano (Mýrdalsjökull glacier). This area has had regular earthquake swarms over the year. Why is not clear. There is no clear signal of magma movement in this area. Torfajökull erupts highly Felsic magma that’s mostly explosive and some type of magma that can flow as a lava flow (maybe in later stage of an eruption, I don’t know for sure).
Earthquake activity in Torfajökull volcano. Copyright of this image belongs to Icelandic Met Office.
The largest earthquake in this swarm had a magnitude of Mw3,2. It was felt in nearby tourist areas and caused few rock slides. Icelandic Met Office is still warning against rock slides because of this earthquakes close to the earthquake swarm location. There is a ongoing risk of more stronger earthquakes in this area of the volcano at the writing of this article.
Since 14. July 2023 there has been a minor earthquake swarm close to Skjaldbreið lava shield just south of Presthnjúkur volcano. Largest earthquake took place yesterday (20. July 2023), with a magnitude of Mw3,0.
Earthquake activity close to Skjaldbreið lava shield. Copyright of this image belongs to Icelandic Met Office.
This is tectonic earthquake swarm and its just normal activity. Its not connected to eruption in Fagradalsfjall mountain, because its outside of that area influence. This earthquake swarm is ongoing at the writing of this article.
This article is short. The eruption is mostly stable at the writing of this article but the situation can change quickly without warning.
The eruption has changed in last few hours. It seems to be in only one crater that is slowly forming. The eruption has stopped at the north most end of the eruption fissure. At the writing of this article.
The dyke now extends 1 km under Keilir mountain in the direction of north-east. This might be a new dyke intrusion and not connected to the dyke that started the current eruption. This might result in a second eruption soon, but its too early to know for sure at the writing of this article.
The eruption started large fires in the moss and other plants in this area around Litli-Hrútur. This has resulted in massive toxic smoke in this area.
There’s a high risk of the volcano gas from the eruption, along with the toxic smoke from all the plants and moss burning.
Interestingly, while earthquake activity has dropped it has not stopped. Why that has happened is a bit of a mystery, it might be connected to the possible new dyke that has formed under Keilir mountain.
Yesterday (10. July 2023) the longest the fissure extent was at 1500 meters or 1,5 km. Since then it has gone down to one erupting crater that seems to be 50 meters to 100 meters long.
Map of the danger area around the eruption. The orange area is the danger zone that people should not travel over. Copyright of this image belongs to Icelandic Met Office and others.
It is impossible to know how long this eruption is going to last. Since dyke intrusions are poor magma containers this eruption might be a short one if there isn’t a constant supply of fresh magma from the deep mantle. Its too early to know if that is the case here. I have also noticed that once the eruption ends in any area, that area is not going to erupt again. When the eruption ends, it ends forever and that makes this a single eruption activity or crater rows. This area might be Monogenetic volcanic field (Wikipedia).
Since this type of eruptions are mostly uneventful and just continue. I plan on only posting updates when there are some news or changes to the eruption happen.
Update at 17:41 UTC
ISOR is reporting that their station called FAF (Fagradalsfjall) has to be moved because the lava is flowing directly at it. They are going to find a new location for this station. This report can be seen here on Facebook in Icelandic.
This is a short update because events are changing quickly.
Length of the eruption fissure is uncertain, reports are conflicting. The numbers I’ve seen are from 200 meters to 900 meters long. This also might be a case of growing fissure eruption.
Harmonic tremor on the SIL station Fagradalsfjall continues to grow. Suggesting that the eruption is increasing in power since it started. This sometimes happens in lava eruptions.
The lava is flowing to the south. It might reach Meradalir valley in about one week to three weeks. Some of the lava is flowing to the north, but a lot of less of it and is only expected to flow in the nearby area. There is no risk at current time for any damage to infrastructure or property.
There’s a risk of new fissures opening up in this area without warning.
This area is remote and difficult to go towards. Police has closed roads for the time being for safety reasons.
I’ll post new update soon as I have any new information or if anything changes. Experience has shown that this type of eruptions are rather uneventful for a longer time periods. I’ll adjust my updates in accordance with that.
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