…its people and its volcanoes.
Why?
Iceland is an interesting place at any time, but with Askja Volcano apparently up to something just now, and with most boffins not yet publicly commenting on it, I did a little reading on the Askja system this week and realized that we need to level up a bit for this one.
It’s not hard, and there are a couple of delightful videos to help us do this.
The people
First, a general introduction to the people and the place (a/k/a geography):
Next, some geology. They don’t even try to use Icelandic pronunciation in this next video, so we’re all safe from alcohol poisoning.
And while serious, this is also a treat to watch.
The volcanoes
It’s an episode from the History Channel’s “How the Earth Was Made” series and originally aired in April 2009; THC made it available on YouTube in 2020.
Before getting to the leveling up, here are a couple of neat background facts:
- This video features, among other scientists, Dr. Mike Poland, who is now very well known as scientist-in-charge at the Yellowstone Observatory. Cool!
- Towards the end, they also interview Þorvaldur Þórðarson — ‘scuse me, Thorvaldur Thordarson — who is at present the one (and thus far only, as far as I know) volcanologist talking publicly to the media about a possible eruption at Askja.
He also is a coauthor on one of the two papers I read (cited at end of post).
A caveat
This video is from an era that emphasized doom’n’gloom when covering volcanoes; please don’t abandon all hope after watching the ending.
Today, fourteen years afterwards, research on glaciers and what triggers eruptions is complex and ongoing. The subject would make a good post, or even possibly an eBook, in its own right.
Leveling up
We’ve already done the “work” by watching that last video.
Just a few points now to carry through to next time:
- Iceland volcanoes are different because of the Mid-Atlantic Ridge and the hotspot plume.
What’s important to know here is that, besides the central volcano, you also have to consider each volcano’s associated fissure system.
Sometimes, as at the recent Reykjanes Peninsula eruptions along the southwest coast, there isn’t even a central volcano!
- Near Askja, but under Vatnajokull ice cap, are the central volcanoes Bardarbunga and Grimsvotn. Their fissure systems extend out beyond the ice.
I think Bardarbunga is in between Askja and Grimsvotn on this map. Note that this whole area is where two segments of the Mid-Atlantic Ridge join up in a triple junction. (Image: Chris urs-o via Wikimedia, CC BY-SA 3.0)
These volcanoes are located above the inferred head of the mantle plume and last erupted at Bardarbunga/Holuhraun in 2014-2015.
This was the one where much of the online world first realized that drones can provide AWESOME video of eruptions.
Because you and I have leveled up, it’s worth pointing out that this lava came up through a fissure group called Holuhraun, in between Bardarbunga, sitting under the Vatnajokull ice cap, and Askja volcanoes.
There is some debate over which of the two central volcanoes is connected to Holuhraun.
The Laki fissures discussed in The History Channel video are not anywhere near this, but they are associated with Grimsvotn.
Relax.
No one is saying or even implying that another Laki 1783-style eruption is looming.
That area is well monitored — accumulation of such humungous quantities of magma presumably would cause a lot of ground deformation and increase in other precursors long before it broke through the ground.
This layperson’s impression is that there apparently is just one fairly large slug of unerupted magma down there, how much I don’t know, left over after this underground dike intrusion happened in 2014 and fed the Holuhraun fires:
Tim Greenfield/Cambridge Volcano Seismology Group
What will it do now?
Let’s look at that next time. The take-away today is that this particular part of Iceland is so intricate that many volcanologists probably are reserving public comment on the restlessness at Askja.
I’ll bet they’re very busy in the field and in the monitoring centers right now.
Reading done:
Hartley, M. E., and Thordarson, T. 2013. The 1874–1876 volcano‐tectonic episode at Askja, North Iceland: Lateral flow revisited. Geochemistry, Geophysics, Geosystems, 14(7): 2286-2309.
Sigmarsson, O., and Halldórsson, S. A. 2015. Delimiting Bárðarbunga and Askja volcanic systems with Sr-and Nd-isotope ratios. Jökull, 65, 17-27.
A little lagniappe:
What would you do for some basalt?
Sampling the Holuhraun flow.
Some people, while not that dedicated, do get very excited over basalt.
Featured image: Nick Fox/Shutterstock
Flight To Wonder 