Category: Lava

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Few points about Iceland geology

Here are few points about geology in Iceland (just because I cannot sleep at the moment). This is also a offshoot of this blog post here.

The basic thing that needs to be known about Iceland is the fact that it is just a island over a hot spot. In every other terms it behaves as expected by a volcanic island on a rift zone. There is a lot known about Iceland geological features and volcanoes. But there is also a lot unknown at the moment. There is nothing mysterious or strange about that. We just don’t know this at the moment, but in the future we hopefully are going to know this. As each eruption or earthquake swarm teaches us more about Iceland and how it works.

I have seen a lot of wrong things about geology in Iceland on this blog in past few days. For instance the claim that energy travels trough a fault zone with N-S bearing (mostly). The volcanoes in question where Hengill volcano and Hekla volcano. This volcano do not exchange energy over SISZ. It simply just does not happen, as law of nature does not allow for it to happen. The following natural laws prohibits this energy transfer (and there is no way around it), Laws of thermodynamics, Inverse-square law, Conservation of mass, Conservation of energy, Momentum, Angular momentum and whole a lot of other physical laws that apply in nature.

I know one of two thing about physics too. As I fully apply that when I am considering what a volcano or a earthquake swarm might be up to in Iceland.

The evolution of Iceland during the past ~20 million years is also a factor in this. As there are many fully formed rift zones, but there is also a lot of failed rift zones in Iceland. There might even be new failed rift zones being formed today. But it impossible to know that for sure at given time. Since we have no way of knowing what is “new” and what is “old”. Research into this matter is going to shed some light on it. But that might take years of hard work of scientists for years to come.


The basic evolution of Iceland from 15milyr ago until the today. Copyright of this image belongs to its owner.


This is the best picture that I know of what they think is the Iceland hotspot. Copyright of this image belongs to its owner.

There is also the thing about the crust in Iceland. But it is believed that part of it might be from a old continent. But majority of it is currently covered with newer layers of rock and sediments. But studies have also suggested (or proved) this. The following papers can be read on this subject.

Older crust underlies Iceland (pdf)
Continental basement under Iceland revealed by old zircons
Continental geochemical signatures in dacites from Iceland and implications for models of early Archaean crust formation (ScienceDirect)

This in part explains the difference in crust thickness when it comes to Iceland.


The thickness of the crust in Iceland. Copyright of this image belongs to its owner.

All pictures above are from this study into the Iceland mantle plume (they are trying to disprove it existence). Iceland & the North Atlantic Igneous Province

Here is a different map of Iceland volcanoes, fissure swarms and age of the lava fields.


Iceland and its volcanoes. Copyright of this image belongs to its owner. This picture is from this web site here, Post-glacial rebound of Iceland during the Holocene Click on the picture to get full size.


Similar map. But in colour. Copyright of this image belongs to its owner.

I hope that this clear few things up about Iceland and how it works and might work. Since we are still learning and there is a lot of things that we do not know about how Iceland actually functions. But me and professional geologists and scientists are doing there best to learn about how Iceland works.

If there is a claim about Iceland that just sounds crazy, it probably is crazy and not based in any actual fact about Iceland and the geology that makes up Iceland.

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Few right and wrong things about geology in Iceland, part 1

I have seen many speculations on how geology works in Iceland. Some of it is good and based on observation and factual basic. Other however is nothing but speculation and far from anything based on factual evidence on how geology works in Iceland.

Few right and wrong things about volcanism in Iceland

Volcano interaction Status: Limited truth to this

Volcano interaction is something of a debated among scientists. But what is not debated is the interaction between volcanoes that lies far apart. That interaction is none by it’s nature. So while I have been seeing discussion in the comments here that there is some connection between activity between Hengill volcano and Hekla volcano. This is untrue. There is no connection between those volcanoes and never has been. The reason is simple. The volcanoes are far apart. They don’t even share the same magma source. But that is evident by the lava that comes from this two volcanoes. But Hekla volcano has mixed types of eruption sometimes. But Hengill volcano only has Hawaii styles eruptions (if not hit by water) when it erupts, in style with other volcanoes on the Reykjanes ridge rift zone.

The only real life examples of volcano interaction are from Bárðarbunga volcano and Torfajökull volcano. The reason for this interaction is quite simple and logical one. Bárðarbunga fissure swarm cuts right trough Torfajökull volcano. When magma travels south-east in the fissure swarm (it last happened in the 15th century) it can hit the magma inside Torfajökull volcano. When this happens there is a big bang in Torfajökull volcano. As the magma in Torfajökull volcano seems to be colder and more Intermediate (andesitic) [link, Wikipedia] in nature. But in Bárðarbunga volcano the magma is Mafic (basaltic) in nature. When the two magmas mix, it ends with a bang and eruption in both volcanoes. But normally the process that starts this is because there is a ongoing eruption in Bárðarbunga volcano. So when Bárðarbunga volcano. I would worry about that rather then anything else.


See, no connection at all between Hekla and Hengill volcano. Copyright belongs too this picture owner. Owner unknown to me.

Iceland is going to have VEI-8 eruption. Status: Not likely.

All volcanoes can do a VEI-8. But the thing is that they are just not likely to do so. As the size of the eruption is directly connected to the inflow of magma it is getting. In the case of Icelandic volcanoes the inflow just seems to be few magnitude too small to make a VEI-8 eruption. The largest VEI eruption known in Iceland was a VEI-6 eruption that took place in Bárðarbunga volcano in the year 1477 (?).

As for VEI-8 eruption. I am not expecting that type of eruption any time soon in Iceland.

Iceland is one volcano. Status: False.

The simple answer is no. The long answer is. Iceland has many volcanoes, not just one. So the answer is no to this.

Geology in Iceland is well understood. Status: False

Geology in Iceland is understood. But far from being fully understood. As it happens geology science is just starting to now understand what complex progress are taking place in Iceland. A lot have been learned. But a lot more needs to be learned about how geology works in Iceland.

Volcano eruptions comes in active cycles. Status: True

This has been observed by actual data. But volcano activity happens in periods of 80 to 160 years. With a quiet period of 50 to 90 years. But numbers are approximation. During the quiet time there are fewer eruptions and they are smaller (hint: Large eruption can still happen however during the quiet period). Last quiet period started in around the year 1870 and did not end until the year 1983. But that year there was a eruption in Grímsfjall volcano. But then Grímsfjall volcano had not erupted since the year 1954, but that break was 29 years long for Grímsfjall volcano.

This graph here also shows this clearly. But this is volcanism in Iceland during the years 1875 and to the year 1993.


Copyright holder unknown. Copyright of this picture belongs to this owner.

It is impossible to know for sure when the high peak in the current cycle is going to be be. But most geologist are estimating that to be sometimes from the year 2020 and to 2080 or about that. So the years ahead is going to be quite busy in Iceland in the terms of volcano activity.

I am going to write more right and wrongs about Icelandic volcanoes soon. But for now this is good enough.

Sources and other things.

Volcano-tectonic Interaction in the Hengill Region, Iceland during 1993-1998 (pdf)
Volcano geodesy and magma dynamics in Iceland (ScienceDirect)
Interaction between Continental Lithosphere and the Iceland Plume—Sr-Nd-Pb Isotope Geochemistry of Tertiary Basalts, NE Greenland
Tomographic evidence for a narrow whole mantle plume below Iceland (ScienceDirect)
Pdf document on Hengill volcano crustal deformation.
Magma (Wikipedia)
Volcano geodesy and magma dynamics in Iceland (pdf)

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New pictures of Eyjafjallajökull Gígujökull glacier lava field

Rúv News has just published new pictures of Eyjafjallajökull volcano. The pictures are from Fimmvörðuháls lava field and the lava field that is in Gígujökull glacier. But in that area a lava flow did take place during the eruption. That lava field has not been explored before. According to the news, a moss has already started to grow on the new lava on Fimmvörðuháls. The Gígjökull glacier has already started to cover the lava field that did melt it during the eruption of 2010 in Eyjafjallajökull volcano.


From Gígjökull glacier. Picture from Rúv News. Copyright holder of this picture is Rúv.

The news of this can be found here. This is in Icelandic.

News from Rúv.

Undraveröld í Gígjökli (Rúv.is, Icelandic, Picture, Video)