Deep inflation detected in Fagradalsfjall mountain

According to a news report today (16-November-2021) inflation has been detected deep under Fagradalsfjall mountain, that is part of Krýsuvík-Trölladyngja volcano system. This inflation suggests that an eruption might start again in Fagradalsfjall mountain, it remains impossible to know when such an eruption might start. Since there is a lot that suggest this inflation is because of magma collecting at depth under Fagradalsfjall mountain. When or if that results in a eruption in the future is impossible to know.

This inflation is now large enough to be seen on satellite images that monitors deformation in the upper crust. In the upper crust this deformation appears small, but that is not all the story in this.

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Earthquake activity west of Kleifarvatn lake

Yesterday (28-October-2021) two earthquakes with magnitude of Mw3,6 and Mw3,0 took place west of Kleifarvatn lake (in Krýsuvík-Trölladyngja volcano system). The first earthquake with magnitude of Mw3,6 took place at 18:36 UTC and the second earthquake with magnitude of Mw3,0 took place at 23:11 UTC. Other earthquakes that took place where smaller in magnitude.

Earthquake activity west of Kleifarvatn lake. Two green stars on top of each other show the strongest earthquakes.
The earthquake activity in Krýsuvík-Trölladyngja volcano system. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity seems to be connected to magma movements in the area. It has not yet and might not result in a eruption since this is in a different fissure area. It is unlikely that this activity is connected to the magma movements that are ongoing close to Fagradalsfjall mountain.

Fewer earthquakes close to Keilir, no eruption in Fagradalsfjall mountain for almost one month

Earthquake activity continues close to Keilir mountain. But it remains at depth of 5 to 6 km and doesn’t show any sign that it is about to move to the surface. More than 10000 earthquakes have been recorded and 18 earthquakes have been recorded with magnitude above Mw3,0. This is according to Icelandic Met Office.

Earthquake activity close to mountain Keilir marked by a green star close to it of the map on Reykjanes peninsula
Earthquake activity close to Keilir mountain on Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

The eruption in Fagradalsfjall mountain (more information at Krýsuvík-Trölladyngja website at Global Volcanism Program) has not been active since 19-September-2021 and there are no signs that the eruption is about to restart soon. Global Volcanism Program no longer updates its information for this volcano as an active eruption. Icelandic scientists in eruptions have not declared the eruption over. It should be expected that the eruption in Fagradalsfjall mountain is over for now, but it can start again at the same location or at new location in few weeks time or maybe even few years from now.

Ongoing earthquake swarm close to Keilir mountain

The earthquake swarm with Keilir mountain continues today (2-October-2021) and largest earthquake at the writing of this article had a magnitude of Mw4,2. This might change without warning.

Green stars on Reykjanes peninsula close to the mountain Keilir. Shows where the current activity is.
The earthquake activity close to Keilir mountain. Copyright of this image belongs to Icelandic Met Office.

Based on what I am seeing it is my view that magma is the reason why this earthquake activity is happening. The magma seems trapped, based on the earthquake activity and that is interesting. This suggest that the feeder channel, that possibly started at this location has closed up and that is the reason why the eruption in Fagradalsfjall mountain stopped. At least that is the working idea, if it is true I don’t know.

Department of Civil Protection and Emergency Management and Icelandic Met Office has warned people against going to Keilir mountain because of risk of volcano eruption or large earthquakes.

It is unclear at the writing of this article if there are changes to hydrothermal activity close to Keilir mountain. There have been reports about it, but they remain unconfirmed at the writing of this article.

There is now a risk of an earthquake with magnitude of Mw6,0 in the area of Keilir mountain. The earthquake activity shows a pattern of high and low activity every few hours. Why this happens is not well understood at the writing of this article.

Earthquake activity south of Keilir mountain

On Saturday 25-September-2021 an earthquake swarm started close to Keilir mountain, at the writing of this article this earthquake swarm is ongoing.

Red dots on Reykjanes peninsula show the location of an ongoing earthquake swarm that is now happening.
Earthquake swarm on the Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

The eruption in Fagradalsfjall mountain has been having its longest quiet period since 19-March-2021 and at the writing of this article that is ongoing situation.

This earthquake activity suggest that the eruption time period in this part of the Reykjanes peninsula is not over, even if nothing is happening at the moment.

Krýsuvík-Trölladyngja is a volcano system is currently erupting in this area.

Article updated on 29-September-2021 at 11:49 UTC. Correct date of the earthquake swarm start added to the article.

Massive lava cave opens up, results in lava flood down to Nátthagi

Yesterday (15-September-2021) around 11:10 UTC a large lava cave just south of the crater in Geldingadalir had a roof collapse in a small area or a lava breakup in the surface. This resulted in the lava flow down Geldingadalir into Nátthagi. The flow covered Geldingadalir in less than 20 minutes. After that it did reach the barrier that stops it from going into Nátthagakriki, if that happens both walking path A and B are going to get closed forever or having to be redrawn from their current locations. Lava down that path also allows the lava flow to go in the direction of Grindavík town and nearby roads.

The lava flow yesterday did go down into Nátthagi but didn’t get far into there compared with the older lava it was flowing on top of. This sudden lava flow did put people in danger and shows that the lava field is full of dangerous caves that can collapse or burst open at any time without any warning. The lava flow that started yesterday is ongoing best to my knowledge. But the view has been limited due to fog and bad weather in Fagradalsfjall mountain this evening.

One or two idiots where seen walking on the crater rim yesterday and I think this are the same people that Icelandic coast guard had to transport from Gónhóll since they where unable to get back because of the new lava flow that had happened when they where there.

The crater is now ~334 meters above sea level high. Currently the crater is now growing in height but that can change without warning.

Pictures of this new lava flow are on social media. I can’t use them because of copyright but if searched they can be found and viewed. There are also some amount of videos of this lava flow on YouTube.

Fagradalsfjall mountain is part of Krýsuvík-Trölladyngja volcano system.

Update on the Fagradalsfjall mountain eruption on 12-September-2021

This is a late and short update on the eruption in Fagradalsfjall mountain on 12-September-2021. Fagradalsfjall mountain is part of Krýsuvík-Trölladyngja volcano system.

Yesterday (11-September-2021) at around 05:00 the harmonic tremor on SIL stations around Fagradalsfjall mountain started to show an increase in harmonic tremor after a break of 8 days. It took few hours for the magma to reach the crater and lava was visible in the crater around 12:00 UTC.

Harmonic tremor chart in purple (lowest frequency), green (mid range frequency) and blue (highest frequency) that shows in the increasing harmonic tremor by rising at the end of the link up to 6000 units (not defined) at 00:38 Icelandic time.
Increasing harmonic tremor at 00:38 UTC on Fagradalsfjall mountain SIL station. Copyright of this image belongs to Icelandic Met Office.

There have been possible new vents been opening up yesterday and today in the lava field. Icelandic Met Office says that this is a lava flow under the old colder lava and is now breaking up and looking like new vents. I don’t know yet if this is accurate, but it is my early assessment that this are new vents and are going to build new crater, at least there is a possibly of crater building if the new vents stay active long enough.

If this are new craters as I suspect, then they are going to change the lava flow quickly and increase the output of the lava flow from what it was. It might soon start to flow down into Nátthagi and other locations that are nearby.

It is a big question if the cycle eruption with no activity for hours has stopped for now. If this has turned back into an eruption that goes in 24 hours a day, that is going to allow the lava field to reach a lot more distance then before.

Update on the eruption in Fagradalsfjall mountain on 19-August-2021

This is a short update on the five month eruption day in the Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

  • The eruption continues its strange cycle of not erupting for few hours and erupting for few hours.
  • The consequence of this type of eruption is that the lava doesn’t flow that far from the crater. It just piles up next to the crater making the structure ever higher. I am currently estimating (this is a guess and might be wrong) the crater at 200 meters high (-+ 50 meters).
  • The eruption has now been going on for five months. Holuhraun eruption in Bárðarbunga volcano in 2014 to 2015 lasted for six months.
  • At the writing of this article there are no new craters open but it doesn’t rule out that new crater might have opened but are hidden under the amount of lava that is around the main crater. As there are some extreme large caves in this lava field. Allowing for a lot of space for new crater to form and start erupting unnoticed.

There are no more updates of the eruption at the writing of this article. That might change without warning but I don’t know if that is going to happen.

Update on the eruption in Fagradalsfjall mountain on 16-August-2021

This is a short update on the eruption in Fagradalsfjall mountain that is part of Krýsuvík-Trölladyngja volcano system.

  • New crater has been confirmed in the eruption in Fagradalsfjall mountain. This crater started to form few days ago. It follows the activity in the largest crater and remains inactive during the time period when there is no activity in the large crater.
  • This new crater is going to change lava flows in the eruption and restart lava flows in the south-Meradalir and Geldingadalir.
  • Current the new crater is building up. It is on the larger crater rim and might be unstable and collapse are likely to happen.
  • Formation of new craters following the formation of this crater is likely. When and where new craters form is impossible to know in advance.
  • It is a question if this is a new phase of the eruption. I currently don’t have an answer.
  • The new crater is visible on all the web cameras.

Fog has been blocking the view of the eruption today and I expect that is going to be the case tomorrow (17-August-2021) and maybe next few days. This fog makes it difficult to see what is going in the eruption.