Bardarbunga

[bjdeming]

Not a surfing cry -- it's one of Iceland's "big guns" and today had an unexpectedly strong seismic swarm as it reinflates after a spectacular 2014-2015 eruption that caused a caldera collapse as well as big lava flows through the Holuhraun fissure system.

It isn't erupting, nor is anything obviously on the way any time soon, but the Icelandic Met Office did issue a couple of aviation notices today as well as an update on their web site.

The situation is complicated (to this layperson, anyway) by some glacial outburst flooding that began this week at nearby Grimsvotn. This complicates things at Bardarbunga because, in the opinion of some volcanologists, in 1996 activity at B. triggered eruption at G.

That hasn't yet been settled AFAIK, but the two "big guns" do sit under the same glacier, and it's best to have an open mind, I guess.

Anyway, here are some links on Bardarbunga and IMO's update today via Google Translate:

• The Icelandic Met Office (IMO): Updates; VONAs (Volcano Observatory Notice to Aviation); Bardarbunga-Holuhraun 2014-2015 eruption.
• IMO’s Bardarbunga information and monitoring page.
• Global Volcanism Program page
• London VAAC advisories page.
• Iceland Monitor event page.

A powerful earthquake swarm in Bárðarbunga began this morning. The largest earthquake was M5.1.

About 130 earthquakes have been recorded since this morning. The most powerful earthquake swarm since 2014, when the Holuhraun volcano erupted.​

14.1.2025

Updated January 14 at 4:30 PM

• After 9 am this morning, the intensity of the tremors decreased significantly.
• It is unclear whether the surge is fading or will pick up again.
• The aviation color code for Bárðarbunga remains yellow.
• The volcano is unusually large and there are many scenarios for possible development.
• The development of seismic activity will be closely monitored.

After 9 am this morning, the intensity of the earthquake swarm in Bárðarbunga decreased significantly and few earthquakes have been recorded since then. The intensity of the earthquake swarm was considerable. Despite the reduced activity, earthquakes are still being recorded, and further developments will be closely monitored.

The earthquake swarm began just after 6 am this morning and peaked at 8:05 am when the largest earthquake, measuring M5.1, was recorded. In addition, 17 earthquakes above M3 have been recorded, of which two were at or above M4.

Earthquakes will be reviewed and there may be changes in recorded earthquakes and their magnitude. The aviation color code remains yellow, indicating increased activity compared to normal conditions and uncertainty about the development.

Progress unclear​

Despite the reduced activity, it is not possible to say whether the swarm is fading. Many scenarios are possible for the development of earthquakes in the area. The development of seismic activity in Bárðarbunga and possible volcanic eruptions will be closely monitored. Further information will be published as new data is received.

 

[bjdeming]

Well, maybe this will be a very short thread, which would be great, but that was a lot of M3's, plus the 5-pointer, so they're probably still watching closely even after lowering the Aviation Code back to Green, and if all stays quiet, perhaps will also do some summer fieldwork when accessibility improves.

 

[bjdeming]

Bardarbunga hasn't done anything new, but Benedikt put things in perspective with an mbl.is interview (autotranslated).

Via GT:

The earthquake swarm that occurred in Bárðarbunga on Tuesday last week is considered unusual and such activity has only been seen twice before, in cases that both ended in an eruption.

This is what Benedikt Gunnar Ófeigsson, director of deformation measurements at the Icelandic Meteorological Office, says in an interview with mbl.is (autotranslated).

Via GT:

"So we were just as expecting something more to happen there, but it didn't. But this is clearly telling us that we need to keep a closer eye on Bárðarbunga and can expect it to do something at any time," says Benedikt...

 

[bjdeming]

From the blog: (the linked paper recreates atmospheric conditions in the Northern Hemisphere in 1783 and discusses how Laki/Grimsvotn might have interacted with them; climate effects were bad but limited to north of around 35°N and the indirect effects are speculative):

February 22, 2025, 3:44 p.m., Pacific: The current geoscientist note at IMO:

At 21:04 tonight, an earthquake of magnitude 5.2 occurred in the northern caldera of Bárðarbunga. More than 20 aftershocks have been recorded, the largest of which is 3.1. There are no signs of seismic unrest. There have been no reports that the earthquake has been detected.
Written by geoscientist on duty Feb 22 22:39

Jon Frimann did a post about this ongoing strong quake swarm, too.

I have been meaning to update this post but more urgent events and my writing projects kept me away — it’s only an academic concern, after all.

However, two academic sources — Haraldur Sigurdsson for the University of Iceland’s Web of Science page (Icelandic) and the UI Southern Volcanoes group in a Facebook post — have, respectively, recently brought up Bardarbunga’s Thjorsa flood lava eruption 8,000 years ago and two other large-volume effusive eruptions in the last 2,000 years.

(Katla is in this overproducer’s club, too, with the Eldgja flood lava eruption in the 900s, shortly after settlement and the only known eruption outside its caldera, and so is Grimsvotn, with the Skafta Fires, or Laki as we foreigners call it, in 1783).

A flood lava eruption is small and — key feature — limited in duration compared to large igneous province eruptions like the Columbia River or Deccan flood basalts that can go on for millions of years.

But a flood lava eruption in Iceland is bigger than what we’re used to seeing. See the book “Island on Fire” or some research papers like this to get an idea of what the Skafta Fires were like firsthand.

As Dr. Sigurdsson wrote, the Thjorsa flood lava eruption through Bardarbunga’s Veidivotn fissure system — bigger than either Eldgja or Laki — is considered to have been a result of pressure release as big glaciers melted and the last ice age ended.

Many of Iceland’s spectacular lava shields and other volcanic features were formed then and never AFAIK have shown signs of activity since.

Bardarbunga, near the hotspot, continued on but at “normal” levels, though with bigger output in 800 AD and the 1400s, per the Southern Volcanoes group. In 2014-2015 it had an eruption at Holuhraun that was 1/10 the volume of Laki/Skafta Fires.

During that effusive eruption Bardarbunga’s caldera collapsed as the melt below it flowed out — to be expected.

And then Bardarbunga should have slept for many decades. When it had some 5-pointers last year, Jon Frimann quite reasonably noted that the next eruption probably would take 50 years or so to come on.

And here we are now and he is noting that magma might be trying to reach the surface.

And two highly respected academic sources recently saw fit to mention Bardarbunga’s occasionally high output in public venues — to be clear, without drawing any linkages to the current activity at restless Bardarbunga.

I am not drawing any linkages, either, and just consider it a heads-up that I wanted to pass along. Let’s just keep one eye on Bardarbunga and remember:

• If it doesn’t go off, all well and good, and as it should be only ten years after such a voluminous eruption.
• If it does go off, it likely will be with a “normal”-sized or even small (for Bardarbunga) eruption.
• It is a member of the overproducers’club.
• As volcanologists say in general, even the volcano doesn’t yet know what it will do.