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Smoke clouds and lava as volcano erupts near Icelandic capital – eruption near Reykjavík follows week of small earthquakes in area
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- Published
- Jul 10 2023
- Word count
- 478 words
Are any of our experts willing to comment? @slug, @joeglen are you following this event?
Sorry for the delay in responding! Please take what I say with a pinch of salt as I'm a student rather than a honed academic. I won't be offended if someone corrects me or provides more detail, so please do.
The activity at Fagradalsfjall right now is typical Iceland fare: it's a type of eruption called a fissure eruption.
Iceland is located at the boundary between the North American and Eurasian plates, and is also located at a 'hotspot' where the mantle is especially warm. The volcanic activity is intimately tied with tectonics too. Icelandic volcanoes are contained within volcanic systems. These comprise fissure swarms and/or a central volcano (a couple of Icelandic volcanic systems actually contain multiple volcanoes). The fissure swarms form when dykes (fractures in the crust) are intruded by magmas which collect in the crust in magma chambers. The dykes in turn are caused by tectonic rifting and also the dilation of the crust resultant from magma build-up. The dense seismometer network on Iceland allows volcanologists to track the propagation of these dykes.
So, what causes a fissure eruption?
Lateral flow of dykes
Dykes propagate through the crust as a result of rifting and dilation processes, which also leads to the propagation of magma. If a dyke intersects with a shallow magma reservoir or a pocket of magma, this can facilitate the release of magma as overpressures cause the surface of the crust to crack. Magma continues to flow in laterally which feeds the fissure eruption. Because this is a lateral process, eruptions can occur quite far along the dyke.Crustal failure and vertical/sub-vertical dykes
The crust can 'fail' when stresses are great. If this happens, magma can passively ascend into the new fractures. Where these cracks rupture the surface a fissure eruption occurs. Just as for the 'lateral flow' process, if preexisting magma chambers are intersected by the new vertical dykes then eruptions can be triggered.Eruptions can occur along the fissure swarms, but where the magma chambers of volcanoes are intercepted, eruptions at volcanoes may occur - which is what is happening at Fagradalsfjall right now.
Great write up :) you covered lots of great info!
Volcanic activity on Iceland is pretty common given its geology, and this looks pretty much what is expected. Interestingly, while basalt is the dominant lava type at Iceland, there are some minor rhyolite deposits too!
Oh man hopefully everything is okay out there. It might be the nature of the friends I made in Iceland, but I feel like at least a couple of them kinda wanted to see the lava up close, hoping that they stay safe though! I'm a huge fan of Reykjavik, been there at least twice in the last year and I really loved the people and culture there.