Category: Magma

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Possible dyke intrusion in Fagradalsfjall volcano

Early morning today (10-November-2022) an swarm of earthquakes took place slightly north of the place where the eruption in August 2022 took place in Fagradalsfjall volcano. This possible dyke intrusion was small and only lasted for about 1 hour before it stopped. Depth of the earthquakes was from 5 km to 7 km.

High resolution image of the earthquakes in Skjálfta-Lísa interactive earthquake map from Icelandic Met Office. It shows the dots line up in a fissure like location.
Skjálfta-lísa high resolution map of the earthquake activity. From Icelandic Met Office website.

This activity might give a clue on in what area next eruption is going to take place in Fagradalsfjall mountain. Based on earlier eruption there won’t be any warning before an eruption earthquake swarm starts. In August that eruption started with a minor earthquake swarm, created from a dyke intrusion that was happening. In the hours before an eruption starts there’s going to be a strong earthquake swarm, based on what happened just before the eruption in August. It is interesting if the eruption activity moves north-east, rather than south-west. Why that happens, if it does so, is not something I am clear on why happens.

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Earthquake with magnitude Mw4,2 in Bárðarbunga volcano

Today (31-October-2022) at 14:57 UTC an earthquake with magnitude of Mw4,2 took place in Bárðarbunga volcano. This is a normal inflation earthquake as Bárðarbunga volcano continues to inflate after the large eruption in 2014 to 2015.

Green star and red dots in the center of the image in Vatnajökull glacier shows the location of the earthquake swarm in Bárðarbunga volcnao. Red dots and a green star to the north close to Herðurbreið in a differnet earthquake swarm
Earthquake activity in Bárðarbunga volcano, also in this image the earthquakes from Herðubreið mountain. Image is from Icelandic Met Office.

This earthquake activity is normal and happens every few months in Bárðarbunga volcano.

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Change in the earthquake activity in close to Herðubreið mountain

Sometime yesterday (24-October-2022) a change happened in the earthquake swarm close to Herðubreið mountain. I am not sure when that change happened and it probably took few hours to happen before I detected it. But the change seems to be that now the earthquake swarm is at two locations and not just one. The second change is that the earthquake swarm is now getting more intense. The earthquakes at the writing of this article are minor, only magnitude Mw0,0 to Mw2,7 at the strongest. Nothing above Mw3,0 so far, but that might change without warning. Depth of this earthquake swarm is around 2 to 3 km at the writing of this article.

Two swarms of red dots show the location of the earthquake swarm east of Askja volcano and south of Herðurbreiðartögl volcano. The earthquake swarm is now west and north of Herðubreið mountain
Earthquake activity close to Herðubreið mountain. Picture from Icelandic Met Office.

What is going to happen next is impossible to know. An eruption in this area has not happened for at least 12.000 years or even longer. I don’t know if stronger earthquake activity is required for this area for an eruption to happen. It already is rather fractured from older earthquake activity and rift activity, that makes it possible for magma to have easier paths to the surface without much earthquake activity. That is at least one idea on the situation in this area. I might be wrong on this, since I don’t have information on the finer details of the crust around Herðubreið mountain.

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Earthquake swarm in west part of Fagradalsfjall volcano

This morning on 23-October-2022 an earthquake swarm took place in west part of Fagradalsfjall volcano. Largest earthquake in this swarm so far had a magnitude of Mw3,0.

Green star just west of main Fagradalsfjall volcano. Few blue, yellow and red dots on the map showing earthquakes in other nearby volcanoes
Earthquake activity west of Fagradalsfjall volcano. Picture from Icelandic Met Office.

This earthquake activity is the result of magma pushing up into the crust at around 5 km depth. This is not a large dyke intrusion and possibly won’t result in a eruption, unless there’s a sharp increase in earthquake activity and that has happened (the August 2022 eruption started this way). This is currently a situation that requires monitoring for changes. If anything is going to happen is impossible to know.

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Fissure opens up in south Grímsfjall volcano (no eruption)

A fissure has opened up in south part of Grímsfjall volcano without erupting at this moment. Pictures show that there’s a lot of hydrothermal activity in this fissure. I can see by the Facebook post (link below) that this is a new fissure in a location that it didn’t exist before. Based on recent history, this strongly suggests that this is the area where next eruption is going to happen in Grímsfjall volcano. When and how big such eruption is going to be is impossible to know. This fissure is located around Lat: 64° 24′ 13,476″ N Lon: 17° 13′ 57,282″ W. It possibly is growing and has made holes in the glacier large enough to swallow large cars.

Grímsfjall volcano with few brown sand on Google Earth image. With triangle in the center to mark its location. Location marker in yellow in the right side of the image not far from the brown patches on the image.
The location of the fissure. Picture from Google Earth program.

The Facebook post with pictures can be found here. But you might need a Facebook account to view the pictures. I can’t add them here because of copyright.

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Something is going on in Grímsfjall volcano

This is a tricky thing to write about. Because nothing has started on the surface and might not start on the surface. It seems that something is going on in Grímsfjall volcano. Since the glacier flood is almost over or has finished the harmonic tremor level should have started dropping, it has not done so and I am not sure why that is. This might be boiling of the hydrothermal systems in Grímsfjall volcano when the pressure on the suddenly drops. Currently the harmonic tremor doesn’t look like it has reached eruption levels, that might change without warning.

Rising harmonic tremor, with a high top from storm noise on the 10/10. Colours are blue, green and purple that is barley visible at the end of the line.
Harmonic tremor in Grímsfjall volcano. Copyright of this image belongs to Icelandic Met Office.
One red dot in Grímsfjall volcano in middle of Vatnajökull glacier shown by white area on the map
Earthquake activity in Grímsfjall volcano. This is almost no earthquake activity. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what is going on. Since there seems to have been a change in Grímsfjall volcano after the big eruption in May 2011. What that change is I don’t know. It seems to have slowed down Grímsfjall volcano eruption rate from what it was, its been 11 years since last eruption. It might continue if no eruption starts now following the small glacier flood that just ended.

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Magnitude Mw3,5 earthquake in Krýsuvík-Trölladyngja volcano

Today (12-October-2022) at 14:18 UTC an earthquake with magnitude of Mw3,5 took place in Krýsuvík-Trölladyngja volcano. This earthquake was followed by few smaller aftershocks. This earthquake seems to be happening because of a inflation that is taking place in Fagradalsfjall volcano and this strongly suggests that inflation in Fagradalsfjall volcano is slowly reaching critical levels. There is no eruption expected from Krýsuvík-Trölladyngja volcano as is.

Green star with few red dots just west of Kleifarvatn lake, showing increase in activity in Krýsuvík-Trölladyngja volcano
Earthquake activity in Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity suggests that more stronger earthquake activity is possibly on the way. When it might start is difficult to know for sure. This has been the pattern in recent months. Earthquake activity starts to appears like this and then one day a major earthquake swarm starts. What happens now is a wait and see as before.

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Earthquake activity has started to increase in Fagradalsfjall and Reykjanes volcanoes

Since yesterday (06-October-2022) the earthquake activity has been increasing in the volcanoes Fagradalsfjall and Reykjanes volcanoes. Please note that Global Volcanism Program has updated the informations regarding Fagradalsfjall mountain and now classifies it as its own volcano, this is after a new report and information from Icelandic Met Office. From now on I am going to use that classification when updating on activity in Fagradalsfjall volcano. I’ll not update older articles (too much work), but this also applies to them as such.

This also means that Fagradalsfjall is a new volcano in Iceland.

Earthquake activity in Fagradalsfjall volcano, Krýsuvík-Trölladyngja and Reykjanes volcano. Shown with red, orange and blue dots
Earthquake activity in Fagradalsfjall volcano and Reykjanes volcano along with Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met Office.

Earthquake activity at start of an eruption cycle in Fagraldsfjall volcano are not large. They grow larger once magma has started to push into the crust, until then the earthquake activity only seems to happens with minor earthquake swarms.

Article updated with new information.

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Inflation from start of September in Krýsuvík-Trölladyngja volcano and in Reykjanes volcano

According to GPS data from Icelandi Met Office that can be viewed here for Krýsuvík-Trölladyngja volcano (Þorbjörn) and here for Reykjanes volcano. It seems that a inflation period, at least in Krýsuvík-Trölladyngja volcano started in early September and is ongoing at the writing of this article. Earthquake activity is low at the moment, but the area has already moved a lot in recent earthquake swarms and that might he dropped the crustal stress in the area. It might also explain some of the GPS movements. I have some, but limited understanding of reading GPS data so my assessment might be off, wrong or both.

There also seems to be inflation going on, without many earthquakes in Reykjanes volcano. That seems to be have been going on since start of August. There have not been any eruption in Reykjanes volcano even after repeated inflation and deflation cycles in the volcano. Inflation cycles often have earthquake swarm activity if dyke activity follows an inflation event. That does not seem have happened this time around.

If this inflation continues, in either one or both volcanoes. It is clear a new period of high earthquake activity is about to start on Reykjanes peninsula. When that earthquake activity is going to start is impossible to know. Since recent earthquake and volcano activity has changed how the crust works in the parts of the Reykjanes peninsula where magma has been active. Since hot magma slowly softens the hard rock in the crust at depth and that lowers the earthquake activity. Rather then at the start of an volcano activity, when the crust is cold and brittle, resulting in high earthquake activity before an eruption.

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Magnitude Mw3,5 earthquake south-west of Keilir mountain

During the night of 6-September-2022 an earthquake with magnitude of Mw3,5 took place 1,2 km south-west of Keilir mountain. The depth was 4,1 km. This earthquake was part of a swarm of earthquakes in that same area. All of them smaller than this earthquake.

Green star just south-west of Keilir mountain, with blue dots showing older and smaller earthquakes in the same line to Fagradalsfjall mountain
Earthquakes close to Keilir mountain. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm and activity strongly suggests that a new earthquake time period is about to start. If it is going to end in a eruption like in July – August is a wait and see situation. How this develops is also impossible to know. It seems that for now, this earthquake swarm is over. Earthquake activity is ongoing and continuos on Reykjanes peninsula and has been since 2021 when cycle of earthquake and volcano activity started.

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