In the Icelandic language, there's often confusion over the prepositions "í" and "á", which can be thought of as equivalent to "in" and "on" in English. For example in English, one may debate over whether it's right to say "travelling in a plane" or "travelling on a plane" and in what context. Well, in Icelandic this confusion is greater, and extends to place names. People in different areas have different opinions about which cities you use "í" with and which ones you use "á" with when describing an activity or state of being there. It's usually just safest to go with whatever the locals use for their town, as they can sometimes be rather passionate about the matter. ;)
So I shall be succinct: the earthquakes from the major volcano Bárðarbunga are getting so big that they're feeling them á Akureyri, halfway across the country.
Join us below for another eldfjallavakt.
Between 1950 and 1990, counting aftershocks as distinct events, Iceland received 26 quakes of magnitude 5.1 or greater, meaning one every 1,6 years. 11 of these were 5.3 or greater (one every 3.6 years), and only two of them were magnitude 5.7 or greater (one every 20 years).
I mention this because I want you to understand the significance of the fact that Bárðarbunga has caused, in a 50 hour period, two 5.1 quakes, two 5.3 quakes, and a 5.7:
It's also worth noting that in Iceland, earthquakes aren't generally felt long from the source, which is typical for volcanic quakes. So the fact that people in Akureyri and the Eastfjörds are feeling them is a testament to their power.
We're now in a period of "reduced" activity. I put that in quotes, because the current level of activity would have seemed crazy high from where it was earlier, which in turn seemed crazy high from where it was before, a major storm to begin with. You can see that in this animation:
But it's "reduced" from where it was late yesterday.
Ever the optimist, seismologist Páll Einarsson is back in the press saying in a short article basically that he thinks it's going to die out - although he's been saying stuff like that since the beginning, so I'm going to take that with a grain of salt.
By contrast, an article was posted from geologist Ari Trausti Guðmundsson, who thinks it's most likely to end in one or more eruptions. He says there's no way to know at this point whether there will be an eruption, a short or long series of eruptions, etc, or anything about power, location, timing, whether it would be a lava eruption or ash eruption, etc. However, he says that the development of the dike and increased quake activity suggests a violent outcome rather than everything fading out. He says the science suggests that if it happens outside the glacier that it's most likely to form lava fountains along a row of craters following the fault, such as that which formed Holuhraun in 1797 (the dike is currently nearing the site of that eruption and there's some speculation of the possibility of a breakthrough there) (quick summary: a repeat of the Holuhraun would be good. Reaching Askja would be bad.)
Ari also presents a theory that Bárðarbunga is not to blame, rather Askja. He suggests the possibility that the magma has been coming up in the southwest corner of the Askja system and indirectly causing quakes within Bárðarbunga. Honestly, I have trouble accepting this theory, as it doesn't explain why the Bárðarbunga caldera would subside, among other datapoints - but it's an interesting theory nonetheless.
The article also goes into the results of the meeting of a scientific committee discussing the volcano. They think that there's three realistic possibilities:
1. That influx of magma stops and the quake storm dies down and the result is no eruption.
2. That the dike reaches the surface and an eruption occurs, most likely at the northern end of the dike. In that case it would be most likely a lava eruption with several explosive phases.
3. It reaches the surface and an eruption occurs, but a large portion or all would be under Dyngjujökull. The eruption would lead to a jökulhlaup on the river Jökulsá á Fjöllum and possibly an explosive eruption with ash fall.
Back to volcano news. The rate of magma influx keeps going up. The latest assessment is that 50 million cubic meters entered just yesterday alone, a rate of nearly 600 cubic meters per second (about 3/5ths the average flow rate of Victoria Falls). The dike is now said to be 40 kilometers long, not counting the initial jaunt to the southeast. As of this morning, the end was 10 kilometers out from the glacier and 15 kilometers from Askja.
You can see the progression over time here in this video (sorry, I wasn't recording these particular graphs from the very beginning, it starts a few days in):
Implication time: What does all this mean?
I don't feel qualified to do any sort of projection forward into the future, only to make a few observations.
One, we've seen this current pattern before. Magma surges forward, slows down or stops (widening rather than growing the dike), major quakes and subsidence occur in the caldera, the pressure rises, then the magma surges forward again. See, for example, the "cork popped" event described previously at Bárðarbunga, or what Krafla did for years at a time on a smaller scale. I see no significance to the currently "reduced" activity, wherein "reduced" is giving us the most powerful quakes yet, ones that you can feel halfway across the country.
Two, the main activity in the dike right now is actually back under the glacier - we really don't want a breakthrough there that could lead to a jökulhlaup :(
Three, let's hope for a Holuhraun (or no eruption). Let's hope not for an Askja. Or a Bárðarbunga caldera eruption. Or a wide range of other really bad possibilities.
Lastly... have some pictures. :) These (courtesy of Morgunblaðið) are of the science team setting up new seismometers and other equipment to monitor the volcano.
Oh, and for those who are interested, here's a video of the final concert and fireworks display at Menningarnótt (which opened with an announcement about Bárðarbunga). Bonus points if you can guess who I am in the video ;) (if you guess right, I'll respond in a PM - and don't guess if you've actually met me, that's cheating!)
Update, 12:50 27 august: Add a brand new 5.3 quake into the above list of abnormally intense activity...
Update, 02:15 27 august: ... And a 3.7 in Askja's caldera :(
Update, 02:30 27 august: Askja's quake upgraded to a 4.5. Lots of smaller quakes coming there. Powerful 5.6 in the dike. And why the heck am I not asleep???
Guess I'll find out what's going on tomorrow when I wake up. But this is just crazy...
Update, 09:00 27 august: Good, no more biggies while I was sleep. The 5.6 was reevaluated to 5.2. The Met Office is saying, "It's still too soon to comment on the situation of the Askja quake and its consequences but it'll be important to pay attention to the region." The dike is moving slowly if at all, and there's still some activity back under the glacier. Quake activity remains high.