Yeah, the eruption started and stopped again but based on the ground movement particularly at the Svartsengi power plant and the Blue Lagoon, this is a pause rather than the end. It appears to be at least a rifting event, the previous one (elsewhere in Iceland) lasted for nine years and provided nine eruptions. Two eruptions during the same year, as happened in 2023, is very rare even for Iceland, and it’s now looking very likely to repeat this year.
But, geological evidence from previous volcanic events on the Reykjanes peninsula (where all these eruptions, now 5 since 2021) have occurred, indicates that the several volcanic systems of the peninsula are closely interlinked and when one goes, they are all likely to go. Last time this happened it went on for centuries. Not 800 years of continuous lava flow of course, but frequent bigger and smaller eruptions the traces of which are the current landscape of the peninsula. At least one of the systems reaches all the way north to Reykjavik area, some of the newer housing districts are built on fairly fresh lava. Good idea? Apparently geologists are not buying property there.
Even if it never reaches Reykjavik, the current activity is at the power plant which is very important to a large area, and Blue Lagoon which is the most important single tourist attraction in the country. Plus westward lava flows might intercept the highway between Keflavik and Reykjavik, although at this moment this is not a major risk. But if the unrest spreads from current areas to the systems west, this will quickly become a concern. And these western systems are part of the Reykjanes peninsula system group and presumably connected.
To top it off, Grimsvötn under the Vatnajökul glacier is having a fever. This is quite common and often, but not always, leads to an eruption. There is much less infrastructure around there so even though the potential eruption would be bigger it has good chance to be less problematic. Eruption under ice or water produces ash clouds which affects air traffic like many of us recall but usually only for a limited time and area. The glacial flooding caused by the volcano heating up and melting the ice is currently ongoing, this may result in an eruption.
So the Grimsvötn main caldera hasn’t been a huge problem in historical times. However the late 1700’s eruption in the Laligigar, part of the Grimsvötn fissure system, was a huge event. Half of the livestock and consequently 20 % of human population in Iceland died. But beyond this, the effects had major global scale impacts. So much sulfur dioxide billowed to Europe that there was elevated mortality in the British Islands and to a lesser extent in mainland Europe too. Weather impacts were gloabal, and further deaths from the resulting famines have been attributed to this eruption or series of eruptions. A volcanic winter can be said to have occurred, and this eruption was among the underlying reasons that led to the famine which in turn led to the uprisings which became the French Revolution! Pretty major, huh? See here, it’s terrifying and fascinating:
https://en.m.wikipedia.org/wiki/LakiI have read thet “May you live in interesting times” is a Chinese curse. Maybe Icelandic too? Globally appropriate as a curse, it seems (again).
