Earthquake activity in Grímsvötn (Grímsfjall) and Þórðarhyrna (Thordarhyrna) volcanoes

Sorry for the late article. I’ve been busy in other project that involves taking a lot picture and putting them up on my Instagram that can be found here.

Two earthquake swarms have appeared that I am now keeping an eye out for. This is earthquake activity in Grímsvötn (Grímsfjöll) volcano and then in Þórðarhyrna volcano (Thordarhyrna). Last time Þórðarhyrna erupted was in the year 1902 and that was at the same time an eruption took place in Grímsvötn volcano. Over the last few months there has been increase in earthquake activity in Þórðarhyrna and Grímsvötn volcanoes. Its not completely symmetrical increase in earthquakes, but close to it as of writing of this article. Last time Þórðarhyrna erupted without an eruption in Grímsvötn volcano was in the year 1887 (15th August) to 1889 (?).


Earthquake activity in Grímsvötn and Þórðarhyrna volcanoes. Copyright of this image belongs to Icelandic Met Office.

It is going to be a serious problem if an eruption happens in Þórðarhyrna volcano because that volcano is completely covered with a glacier that is up to 200 meters thick or thicker. Other risk factor is that Grímsvötn volcano might erupt outside of the caldera resulting in glacier floods and other problems.

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Earthquake activity in Þórðarhyrna volcano (Thordarhyrna)

During the night of 3-December-2018 earthquake activity started in Þórðarhyrna volcano (no GVP profile, under Grímsvötn volcano profile). Largest earthquake in this swarm had a magnitude of 2,1 and second largest earthquake had a magnitude of 2,0.


Þórðarhyrna volcano is located south-west of Grímsvötn volcano. Yellow dots on this image. Copyright of this image belongs to Icelandic Met Office.

Last eruption in Þórðarhyrna volcano was in the year 1902 December to 1904 12-January and was a VEI=4 eruption. An eruption happened in Grímsvötn volcano at the same time.

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Earthquake activity in Grímsvötn (Grímsfjall) volcano

During the night of 23-November-2018 there was an magnitude 3,1 earthquake in Grímsvötn volcano (Grímsfjall). Only one aftershock appeared and it had a magnitude of 0,9.


Earthquake activity in Grímsvötn volcano (green star). Copyright of this image belongs to Icelandic Met Office.

No change happened on tremor plots following this earthquake activity. Last eruption in Grímsvötn took place in 2011.

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Earthquake activity in Grímsvötn volcano

During the night there was an earthquake swarm in Grímsvötn volcano. Largest earthquake in this swarm had a magnitude of 2,6 and other earthquakes were smaller in magnitude.


Earthquake activity in Grímsvötn volcano. Copyright of this image belongs to Icelandic Met Office.

Yesterday (06-November-2018) there was also earthquake activity in Grímsvötn volcano but it was at lot smaller scale then what happened during the night. At the moment there are no signs that Grímsvötn volcano are about to erupt. There has not been any more earthquake activity today.

Glacier flood starting from Grímsvötn volcano

Glacier flood has started from Grímsvötn volcano. This glacier flood is expected to be small like last few flood that have happened. At this moment I am not expecting an eruption from Grímsvötn volcano. If an eruption does happen I would not expect it to be a large one.

I’ll update this article or write a new article when I can or if something major happens.

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Slight increase in earthquake activity in Grímsvötn (Grímsfjall) volcano

Over the past few months there has been a slight increase in earthquake activity in Grímsvötn (Grímsfjall) volcano. This increase in activity strongly suggests that Grímsvötn are now in later stages of getting ready for an eruption.


Earthquake activity in Grímsvötn (Grímsfjall) volcano. Close to centre in Vatnajökull glacier. Copyright of this image belongs to Icelandic Met Office.

Last eruption in Grímsvötn volcano was in 2011 and that was a VEI=4 eruption and the largest one in at least 140 years. I don’t expect next eruption in Grímsvötn to be a big one, but there is no way to know that for sure until an eruption happens. When that happens is impossible to know for sure. When next eruption happens is something that is not possible to know. All that can be estimated that a new eruption in Grímsvötn volcano is not far into the future.


This graph gives a good idea the time interval betweens eruptions (last eruptions since 2000). Copyright of this image belongs to Icelandic Met Office.

Since 2000 the time between eruptions is around 2200 days on average. That number of days is about to happen soon in Grímsvötn volcano.

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Harmonic tremor change close to Grímsfjall volcano

There seems to be a harmonic tremor pulse or a change around Grímsfjall volcano. This might be nothing, but the change appears on several SIL stations around Vatnajökull glacier. The harmonic tremor is strongest on Húsbóndi SIL station and Jökulheimar SIL station. This might be something else then magma, glacier movement or sudden flood are an possibility.

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Húsbóndi SIL station. Copyright of this image belongs to Icelandic Met Office.

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Jökulheimar SIL station. Copyright of this image belongs to Icelandic Met Office.

Currently I don’t know what is creating this change in harmonic tremor. I know it is not weather and this is on too many SIL station to be local noise. The SIL station at Grímsfjall volcano doesn’t show any change, so everything is quiet in that volcano. But this is within Grímsfjall volcano fissure swarm that contains the volcano Þórðarhyrna, it last erupted in the year 1902 and has been quiet since (information about eruptions in Þórðarhyrna volcano can be found under Grímsfjall volcano eruption history).

If anything happens I’ll update this article or post a new one.

Small glacier flood from Grímsfjall caldera lake

On the 18th of August 2016 a small glacier flood started from the Grímsfjall volcano caldera lake. This is a tiny glacier flood according to the news, with the glacier on top of the lake only having dropped around 5 meters so far.

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Minor glacier flood as it appears on Grímsfjall volcano SIL station. Copyright of this image belongs to Iceland Met Office.

This glacier flood is going into Gígjukvísl glacier river, at the moment Iceland Met Office doesn’t think there is any major danger from this glacier flood. The biggest risk at the moment is from volcano gases that have dissolved into the water and get released when the pressure drops of the water. The glacier water is already in Gígukvísl glacier river, no major changes are expected in that river due to how small this glacier flood is.

Iceland News

Lítið jökulhlaup hafið úr Grímsvötnum (Rúv.is, Icelandic)
Jök­ul­hlaup hafið úr Grím­svötn­um (mbl.is, Icelandic)

Earthquakes between Bárðarbunga and Grímsfjall volcanoes

Today (05-July-2016) at 05:56 UTC an magnitude 3,4 earthquake took place between Bárðarbunga and Grímsfjall volcanoes.

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The green star is the magnitude 3,4 earthquake between Bárðarbunga and Grímsfjall volcano. Copyright of this image belongs to Iceland Met Office.

This earthquake suggests that an complication is on the way. The question here is if an interaction between Bárðarbunga volcano and Grímsfjall volcano is on the way. Since both volcanoes are preparing for an eruption. [Speculation!] All that I get from my models (in my mind, since I don’t have the computer power or the skills to make them PC friendly at the moment) is confusion. At worst a magma dyke from either Bárðarbunga volcano might enter Grímsfjall volcano or an dyke might come from Grímsfjall and enter Bárðarbunga volcano (hint: A result of either of such event is rather catastrophic eruption, even if just for a short time). What can also happen is nothing, just earthquakes and nothing more. However, increase in the earthquake activity at this location suggests that no such luck is on the way. When and if such event happens is impossible to know, what can be done is to keep monitoring, day and night. This is going to happen the when and the way it wants to happen, all that can be done as humans is to wait and see. [/Speculation!]

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Grímsfjall volcano preparing for an eruption (also known as Grímsvötn)

On Wednesday 25-May-2016 a small earthquake swarm took place in Grímsfjall volcano (also known as Grímsvötn), none of the earthquakes that took place managed to reach the magnitude 1,0, many of the earthquakes where shallow and might be glacier movement, rather than actual earthquakes, but in I find it unlikely reason.

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Earthquake activity in Grímsfjall volcano (red dots, blue dots). Copyright of this image belongs to Iceland Met Office.

Since 2011 Grímsfjall volcano has been preparing for an eruption. The eruption in 2011 was the largest one in 140 years at least (VEI=4). The average time between eruptions in Grímsfjall volcano around 5 to 7 years (based on known eruption history). How long it is going to take until Grímsfjall volcano is ready for a new eruption is impossible to know, the current data however suggests that next eruption might not be that many years away. GPS data and other interesting information can be found here.