Stress related earthquake in Krýsuvík-Trölladyngja volcano system

Today (8. July 2023) at 17:57 UTC an earthquake with magnitude of Mw4,5 took place in Krýsuvík-Trölladyngja volcano system. This is a stress realted earthquake because of the inflation between Keilir and Fagradalsfjall mountain.

Difficult to see in all the activity, on the right there is a green star and a lot of red dots below it. That is where the earthquake took place. There's a lot of activity on this map because of Fagradalfjall mountain.
The earthquake activity in Krýsuvík is on the right on this map. A green star with a lot of red dots under it. Copyright of this image belongs to Icelandic Met Office.

More of this earthquakes are going to happen both east and west of the dyke between Keilir and Fagradalsfjall mountains. Both before an eruption and after it ends. This type of earthquakes can have magnitude above Mw5,0 and they can happen in areas that have been quiet so far.

Update on the activity in Fagradalsfjall mountain on 7th July 2023 at 14:28 UTC

This is going to be a really short article. Because an eruption might be about to start. Difficult to be sure, but there’s a chance. Eruption has not started at the writing of this article.

  • Largest earthquake in the last 24 hours seems to be a magnitude Mw4,3. I no longer can keep up with all this earthquake activity.
  • Inflation in area close to Keilir has reached 200mm (20cm) in less than 48 hours when this started.
  • Inflow of magma is estimated to be 88m3/s and that is a lot of magma moving and moving fast.
A lot of earthquakes in Fagradalsfjall mountain. Too many earthquakes too count and too many green starts.
Heavy earthquake activity in Fagradalsfjall mountain. Copyright of this image belongs to Icelandic Met Office.

It is unclear where the eruption is going to happen. But there has been a drop in earthquake activity that strongly suggest that magma is close to finding a path to the surface. According to measurements, the magma is now less than 1 km away from the surface.

Update on Fagradalsfjall mountain activity at 16:35 UTC on 5th July 2023

This is a short update since there is a lot going on.

  • Largest earthquake recorded at the writing of this article is Mw4,8 from earlier this morning.
  • Larger earthquakes are growing in numbers. There is now also a warning for possible Mw6,3 earthquake on Reykjanes peninsula following this earthquake swarm and dyke intrusion into Fagradalsfjall mountain.
  • The dyke intrusion is coming up just south of Keilir mountain.
  • Based on what I am seeing, it is possible that current dyke intrusion into Fagradalsfjall mountain is larger than the first eruption in March 2021. If this is accurate is a wait and see situation until an eruption starts.
  • It is possible to view the earthquake activity in real time here, at Raspberry Shake website.

 

A lot of green stars and red dots in Fagradalsfjall mountain on Reykjanes peninsula. Time on map is 5. July 2023 at 16:25 UTC.
Heavy earthquake activity in Fagradalsfjall mountain. Copyright of this image belongs to Icelandic Met Office.

All data now suggest that an eruption is going to happen. Where it is going to start erupting is impossible to know and it is not possible to know when it is going to start erupting.

I’ll try to post update when more is known about what is going on.

Update on Fagradalsfjall activity at 11:40 on 5. July 2023

This is a short update since this situation is changing quickly.

  • Largest earthquake recorded so far had a magnitude of Mw4,8 and was felt over a wide area.
  • Uncertainty level has been declared for Fagradalsfjall mountain area because of this earthquake activity and the risk of an eruption.
  • Current depth of the magma is now 3 to 6 km and is getting shallower by each hour.
  • Over 2000 earthquakes have been recorded at the writing of this article.

 

A lot of earthquakes in Fagradalsfjall mountain. Time on image is 11:30 on 5th july 2023.
Earthquake swarm activity in Fagradalsfjall mountain. Copyright of this image belongs to Icelandic Met Office.

The only web camera that I know of at the moment and is showing Fagradalsfjall mountain is this one here. When the eruption starts, it should be visible in some part on this web camera. I hope that other closer web cameras are going online soon. Those where run by Rúv and mbl.is in last eruption.

Earthquake swarm in Fagradalsfjall mountain

Today (4. July 2023) there has been a earthquake swarm in Fagradalsfjall mountain. Largest earthquake had a magnitude of Mw1,6 and at the writing of this article there have not been any earthquakes with magnitude above Mw2,0. This might change without warning.

Red dots in Fagradalsfjall and yellow and blue dots in other places on Reykjanes peninsula.
Earthquake activity on Reykanes peninsula. Copyright of this image belongs to Icelandic Met Office.

Smaller earthquakes swarms sometimes seems to happen before an eruption in Fagradalsfjall mountain. The current earthquake swarm has all signs of dyke intrusion. If that is going to result in eruption now is impossible to know.

Reykjanes peninsula might be one large volcano

It was in the news today (3. July 2023), since inflation has been detected from GPS data on Reykjanes peninsula since start of April. What was told in a interview on Bylgjan (radio channel) and later published on Vísir.is news website (link below, but the whole thing is in Icelandic) is that all of Reykjanes peninsula is inflating. What is also starting to show in the GPS data is that there might not be separate volcanoes on Reykjanes peninsula, this might also have happened in the year 2020 – 2021, before the first eruption in Fagradalsfjall mountain. All of Reykjanes peninsula might be one large volcano, extending from Hengill to Eldey or Eldeyjarboða, the south end might have uncertain location. This changes everything as that means that it can erupt at any location on the Reykjanes peninsula without warning and the whole area is now in an eruption cycle.

The current period of inflation started in April and is now at 2,5cm (25mm) and is centered at the last eruption location in Fagradalsfjall mountain. That means the most likely location of next eruption is going to be Fagradalsfjall mountain. This inflation is also going to trigger large earthquakes on Reykjanes peninsula in next few weeks to months until an eruption starts. Along with the normal amount of small earthquakes that have been happening since April on the whole of Reykjanes peninsula.

I don’t know when or how long it is going to take to change the official definition of the Reykjanes peninsula. Because this is going to require more research and data collection for the scientists in Iceland. This also means a lot of new science papers have to be published and peer-reviewed.

Icelandic news

Fólk á suð­vestur­horninu má búa sig undir reglu­lega jarð­skjálfta (Vísir.is)

Magma detected deep under Reykjanes peninsula

According to a news on Rúv News there has been detection of magma at considerable depth on Reykjanes peninsula. This magma is actively trying to reach the surface, but has not been successful for now. This has resulted in a lot of dyke intrusions on the Reykjanes peninsula in recent months. Earthquake activity seems to follow each inflation period on the Reykjanes peninsula according to the news.

The magma in the deep crust and in the mantle is going to increase in volume until it can break up the surface. How long that is going to take is something I don’t know. Next eruption cycle is going to start with a large earthquake, just like the last one. Based on all current data that I have.

Rúv news in Icelandic

Jarðskjálftavirkni aukist síðustu daga og vikur (Rúv.is)

Increase in earthquake activity in Reykjanes and Fagradalsfjall volcano

During the night of 3. June 2023 an earthquake swarm took place in Reykjanes volcano, at location called Reykjanestá. Largest earthquake in that swarm had a magnitude of Mw3,0. Other earthquakes where smaller. This earthquake swarm suggests a magma movement, but it is difficult to be sure if that is what happened now.

Earthquake swarm out in the ocean next to Reykjanestá and there's also an earthquake activity in Fagradalsfjall volcano. Time on map is 03. june. 23 12:35 (Iceland time)
Earthquake activity in Reykjanes volcano and Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

Its been ten months since last eruption took place in Fagradalsfjall volcano. It is likely that a new eruption is going to happen soon, but it is impossible to know when. In last few weeks earthquake activity has been increasing in Fagradalsfjall volcano and that suggests that magma pressure inside the volcano is increasing. It just has not reached the levels to start a new eruption.

Earthquake swarm north of Grindavík town, next to Blue Lagoon

This morning (25. April 2023) an earthquake swarm started north of Grindavík town, next to the Blue Lagoon. This earthquake swarm is ongoing at the writing of this article. If this is going to result in a eruption is impossible to know. The magma has reached the depth of 2 km and that is not good news if this continues to intensify. Large earthquakes do not need to happen before an eruption starts under the correct conditions in the curst and there has been a lot of dyke activity in Reykjanes volcano in last 3 years. Without that activity resulting in a eruption.

Red dots north of Grindavík town and next to the Blue lagoon on the map (the lagoon doesn't appear on the map). Time on map 25. Apr. 14:00.
Earthquake activity north of Grindavík town. Copyright of this image belongs to Icelandic Met Office.

Eruption at this location would be bad, because of the tourist infrastructure next to this location that is the Blue Lagoon. Only thing that can be done now is to monitor the situation and see if it changes from what is currently happening.

It is possible to view the earthquake swarm in high resolution on Skjálfta-Lísa and other private websites that have similar maps.

Early signs of next eruption phase in Fagradalsfjall volcano

Since end of February 2023 there have been slowly growing signs in form of a small earthquake activity in Fagradalsfjall volcano and nearby area. It is impossible to know when next eruption starts in Fagradalsfjall volcano, but last time the quiet time was around 10 months. If it is going to be shorter or longer now is impossible to know.

Red dots and orange dots, not many of them in Fagradalsfjall volcano, in Krýsuvík-Trölladyngja volcano east of Fagradalsfjall and orange and blue dots west of Fagradalsfjall volcano in the volcano Reykjanes.
Earthquake activity in Fagradalsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

Currently the earthquake activity is minor, but that can change quickly and without much warning. At the writing of this article, its been 6 months and 24 days since the eruption in Meradalir valley ended. I don’t know if this is going to happen the same was as it did before last eruption. Since there’s a lot of magma at depth of 5 to 10 km now and that changes how everything functions and behaves in the crust.