Hey everyone, this just in from Mike Richards, our resident volcanologist:
The latest on the eruption is that it seems to be settling down to a more ‘Icelandic’ style of eruption. The huge ash falls of the last few days are dwindling and most of the stuff coming out of the crater is falling locally. Which means Alda might once again be able to fly to Europe.
In the last couple of days the magma reaching the surface has become more fluid, allowing the gas inside to escape quietly without exploding the rock into ash. At the same time, it looks like less water is reaching the vents, which is reducing the number of steam explosions that were also throwing ash into the atmosphere.
The volcano is now changing between two quite well known types of eruption. The first is called a ‘Surtseyan’ eruption – named after the island of Surtsey which appeared not too far from Eyjafjallajökull in the Westman Islands between 1963 and 1965. Surtsey began life as an undersea eruption marked by violent explosions as seawater crashed into the open vent.
These eruptions continued right up until Surtsey’s vent cleared the sea and began building a mountain. During this time, Surtsey was quite capable of throwing ash several kilometres in the air – but of course in those days there was much less air traffic to worry about.
Eyjafjallajökull’s ice is still melting and water is pooling around the vents. Every now and again it comes into contact with the magma and there is a filthy explosion of ash and ice. You can see one of them in this video.*
(If you’re in Reykjavik there is a superb exhibit about Surtsey at the museum – erm can’t remember the name (Alda???) it’s next to the opera house)
The other type of eruption which appears to be happening at Eyjafjallajökull is called ‘Strombolian’ and is named after, Stromboli an active volcano West of Italy which has been more or less continuously active for the last – wait for it – 20,000 years. Strombolian volcanoes throw out glowing cinders and lava bombs at short intervals of minutes to hours to altitudes of tens or even hundreds of metres. They are the result of very fluid magma and are rarely dangerous. In fact, if you ever go to Stromboli (there’s a ferry from Naples), you can climb the mountain and sit on the edge of the crater and watch the eruption.
If you’re lucky you can see explosions towards dusk.
All of this means that Eyjafjallajökull is in a new phase of its eruption – but that does not mean that the eruption is over or that it will not return to explosive activity. It’s possible there is more sticky andesite deep under the mountain which can’t currently find its way to the surface, or that a new fissure might open under the ice cap.
One question for Alda or any other Icelanders out there. What’s going on on the Westman Islands? From the look of it they’ve been under the plume for the last few days. I understand they also get their drinking water from the mainland.
Thank you Mike!
To address Mike’s question, I haven’t heard lately what’s happening on the Westman Islands, but in a report shown a few days ago it seemed it was just business as usual and they hadn’t been unduly affected by the ash. After all, the plume was blowing to the east, not so much to the south, which is where the islands are.
And as for the Surtsey exhibition … there was one at the Culture House a couple of years back, but I don’t know of one at the present time.
* The link marked with the asterisk also has a diagram [if you scroll down a little] that shows the subterranean channels of the volcano. It shows both the ducts to the Fimmvörðuháls eruption [the nice little tourist eruption we had first] and to the one that’s erupting now [the duct that sticks straight up]. It also shows the close proximity to [gulp!] Katla.