Category: Dyke intrusions

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Extinct volcanoes in Hungathing Vestra county, Iceland

Here is an picture of how an ~5 million year old extinct volcano looks out. This pictures also show an old dike intrusion that might have gone up to the surface on that time. But I think it is hard to know that for sure, as erosion has changed the landscape a lot over the past 10 million years or so. So it hard to know for sure how deep this magma dike did actually form or if it was connected to an crater on the surface.


About 5 to 8 million years old dike intrusion into sedimentary rock that pre-dates this dike intrusion. I do not know by how much older the surrounding rock actually is. But it has small fossils in them.


The volcano that did create this old dike intrusion. The rocks in the area (old lavas) suggest that this was mostly basalt that did erupt from this volcano. But this volcano was on the old Snæfellsnes-Skagi Rift Zone.


Rift Zones in Iceland. Picture is from Wikipedia. See original copy here along with copyright information. Please note that this picture is NOT completely correct in regards to the facts. But is good for basic illustration of the rift zones in Iceland. Note that this is picture is missing the Skagafjörður Rift Zone (failed rift zone).


Picture of what can be seen of the Snæfellsnes-Skagi rift Zone. (I think it is the correct name for it). The mountain behind it is also an massive old volcano that was active at the same time as this rift zone. The houses there belong to my mon and dad (also on the picture below this one). They run an sheep farm.


Picture of Snæfellsnes-Skagi rift Zone to the north. The same volcano as on picture above can also been seen on this picture. But what is not seen is the third volcano that is in this area (also extinct). But glacier activity did remove all major traces of that volcano long time ago.

I am going to post more pictures of this area during the summer. Even if it is just small part of Iceland, it has an lot of geological history to show. All of it is connected to volcanism and glacier activity over the past 8 million years (or about that) time. Too see full size of the pictures, just click on them.

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Grímsvöt eruption appears to be over

Given the current tremor plot on Icelandic Met Office and with reports it seems that the eruption in Grímsvötn (Grímsfjall volcano) is about to be over for now. It is impossible to know if the eruption is going to resume soon or not. But at the moment this eruption seems to be over as it looks now. If it remains like that has to be seen however.

This drop in the eruption has been confirmed by Icelandic Met Office tremor plots.

Tremor plots as of 07:00 UTC. This tremor plots are from Icelandic Met Office web site. Copyright of this pictures belongs to Icelandic Met Office.

Early news this morning in Iceland reported that steam was only coming from the main crater of Grímsvötn.

Other interesting development is that an earthquakes have started to appear SSE of Grímsfjall volcano (Grímsvötn). It is unclear why earthquake are happening at this location. But dike intrusion at this location is not impossible.

The reason for flight problems in Europe is because of the volcano ash that was ejected into atmosphere in the first days of the eruption. It is going take few days for that volcano ash to disappear from the air. Until that happens, it is going to create problems for air traffic.

Update 1: Even if the eruption appears to be over the tremor is still high. I do not know why that is. It is a question why that is or if this is just break in the eruption or not. Only time is going to tell what happens next.

Update 2: There was an news report this morning that before 02:00 UTC there was an spike in activity in Grímsvötn that did shoot the ash cloud up to 8 km. But that spike did only last for few moments before it was over. Rúv has released video here (Windows Media Player) of the eruption site.

Updated at 07:37 UTC.
Updated at 07:50 UTC.
Updated at 08:33 UTC. Blog post title updated.
Updated at 11:42 UTC.
Updated at 12:23 UTC.

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The magma below Upptyppingar tuff mountains

Upptyppingar are a tuff mountains in the east highlands in Iceland. There formation is contributed to a sub-glacier eruption in this area around 12.000 years ago. A second older sub-glacier eruption feature is also present in this area, it is called Álftadalsdyngja. It is believed that it did form around 700.000 years ago in a basalt eruption in this area. Upptyppingar and Álftadalsdyngja are both inside Kverkfjöll volcano fissure swarm.


Map of the area. Copyright of this picture belongs to how created it. Author unknown. Picture is from here.

In the year 2007 (Week 50) a earthquake swarms started to appear in Upptyppingar area. Earthquake activity in Upptyppingar area have continued since then. With total number of earthquakes in this area since the year 2007 is something over 6000 total. The reason why earthquakes are happening in this location is because magma is pushing up trough the crust in this area. This has been confirmed by GPS measurements since the year 2007.

It is my opinion that increased activity in Askja volcano might trigger a eruption in Upptyppingar area or in nearby area. As the risk of dike intrusion from Askja volcano into the Upptyppingar magma sill might trigger a large fissure type of event in this area. This is just speculation based on observed data. So please take note of that fact. The reason why I fear dike intrusion from Askja volcano is due to the changes that Upptyppingar magma has created in the nearby crust. But if this happens depends on how Askja volcano eruptions are going to behave in the future.

Here are some scientific data on Upptyppingar and the magma that has been collecting at 15 km depth below Upptyppingar mountains since the year 2007.

EARTHQUAKE SWARMS AT UPPTYPPINGAR, NORTH-EAST ICELAND: A SIGN OF MAGMA INTRUSION? (pdf, study)


Location of the earthquakes since the year 2007. Copyright of this picture belongs to Icelandic Met Office. Picture is from here.


Depth of the earthquakes in the year 2007. As can be seen, the magma moved upwards with time. Copyright of this picture belongs to how created it. Author unknown. Picture is from here.


Estimated location of the magma below Upptyppingar mountain. This location is based on earthquakes and other measurements. Copyright of this picture belongs to how created it. Author unknown. Picture is from here.

What happens with Upptyppingar is now just a question of waiting and seeing. But there is also a good chance that this magma is never going to reach the surface in a eruption and is just going to cool down there and form a basalt dike that is going to be exposed in few million years when the weather and ice remove the rocks on top of it.

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About the earthquakes north of Askja volcano

The earthquakes that are now taking place north of Askja volcano are interesting for many reasons. One of the biggest reason why this earthquakes are interesting is the fact how shallow they are. But it is also interesting on how small the area the earthquakes are taking place on.

This earthquake activity did start in Week 15 with one earthquake. In Week 16 the activity had grown up to few earthquakes. In Week 17 (current) the activity has continued to grow in this area. This activity currently stands out in the earthquake activity around Askja volcano.

While it is common for Icelandic volcanoes to erupt from a central vent. It is also common for Icelandic volcanoes too erupt from fissures (like Fimmvörðuháls Eruption 2010). One of the clues to this type of eruption close to a central volcano is a earthquake activity. It is my opinion that this earthquake activity qualifies as pre-activity for a fissure eruption in the area of Askja volcano. But if anything happens soon is a different question and it is impossible to predict for now. It is however sure that before such eruption the earthquake activity in this area needs to increase a lot more from the current levels of earthquake activity that are being seen today.

Currently no eruption is immanent in Askja volcano.

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Interesting earthquakes north of Askja volcano

There is a interesting cluster of earthquakes north of Askja volcano. What is most interesting is the fact that this earthquakes are shallow This cluster of earthquakes is most interesting for the fact that it is shallow. The depth of the earthquakes is from 8.4 km and up to 0.1 km (~100 meters). This suggests that this is a dike intrusion is making. But appears to be growing slowly (a bit unclear at the moment however). But at this time it is impossible to know if this possible dike intrusion makes it too the surface or not.

History tells that it is not unclear for Askja volcano to erupt in small fissures. But that last happened in the Askja eruption in the year 1961.

Currently it is unclear what is going on north of Askja volcano. But this is for sure evolving into something in my opinion. But the question remains how long this is going to take. But this process has already been ongoing now for about 14 months and counting.

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Interesting earthquakes 20 km WSW of Laki in Eldgjá volcano canyon (Katla volcano fissure system)

There are interesting earthquakes about 20 km WSW of Laki. The locations of the earthquakes suggests strongly that they belong to Katla volcano fissure system. Last eruption in this area took place around the year 934. When the Eldgjá volcano canyon was formed. That eruption did destroy a older volcano canyon located in this same area (lava flows volcano ash did fill up that canyon far as I know).

The earthquakes that have been taking place in this area are small. The largest so far has the automatic size of ML1.2, but only ~4 earthquakes have been recorded so far. But what is most interesting about this earthquakes is the depth. The earthquakes that has the best automatic detection by the SIL system has the depth of 0.7 km. But that makes the depth of ~700 meters and that is a shallow earthquake. Given that this area has only fissures and no activate volcanoes. It is not unheard of in Iceland that a fissure eruption to start with no warning at all. Last time this did happen was in Gjálp eruption in the year 1996. Before that a dike intrusion into the bedrock did manage to get to the surface in Askja eruption in the year 1878, when a 25 km long volcano fissure did open up (small compared to Eldgjá eruption around the year 920).

I do not know what is going on in this area at the moment. As the activity so far has been too small to make any clear picture of it. But Katla volcano is a big volcano and it is not out of volcano league to make a new fissure eruption instead of the regular caldera eruptions under the glacier as Icelanders have gotten used to over the past 1000 years or so. Last time this did happen there are suggestions that there was a also a eruption at the same time in Katla volcano caldera. But that this has only been revealed during research over the past 50 years or so in this area.

I have also noted that there is a small increase in earthquakes inside Katla volcano caldera, not far from Austmannsbunga. But at this moment it is too early too know what it means for sure. There is no eruption is imminent in Katla volcano when this is written. Just too be clear on that fact.

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Possibility of dike intrusion in Hamarinn volcano

It appears that there is a chance of a dike intrusion in Hamarinn volcano (Loki-Fögrufjöll area). What suggest that there is a dike intrusion starting in Hamarinn volcano is a earthquake swarm that is unusually dense and has a really narrow area. But normal earthquake swarms usually spread over a small area in the align of the fault line.

How this is developing is a good question. But due to lack of earthquakes it is hard to know for sure at the moment. But at the moment it is worth to keep eye on Hamarinn volcano area.

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Dike intrusion starting in Torfajökull volcano ?

There was a small earthquake at 23:50 UTC in the Torfafjökull volcano. The earthquake it self was only ML1.7 in size, but the depth was 15 km. But that depth indicates that the earthquake was started by magma rather then tectonic process in the area. This would mean that a dike intrusion was starting in Torfajökull volcano at present time.

I did record this earthquake on my geophone, but this earthquake had a magma looking signature in it. But it was not clear and hard to see due to a minor weather effect in the area. Torfajökull volcano is not monitored with GPS instruments at the moment.

This is unlikely to be a pre-event to a eruption in the area. But dike intrusions appears to be a common events in Torfajökull volcano.