The eruption is now some 10 days old. In some ways it has progressed as expected. The row of cones has focussed on one spot, although surprisingly it produced a twin (after exterminating the minor third). The lava is filling the valley but has not found an escape so remains well confined. The Icelanders are flocking towards the eruption: with scant regards for safety. The hill side next to the cone is no longer accessible (phew) but otherwise the sightseers get so close that it is at time hard to see what is smoke from the lava and what from the barbeques. I guess it helps not having to bring your own heat. For the people unlucky enough not to live in Iceland, two cameras have been put up with excellent eruption viewing, freely available worldwide. And of course, those showy Icelanders are using the camera to showcase their lives to the world. Their dogs, their clothes, their phones (a bit creepy to see someone on my screen take a photo of me), even their love lives. (Erupt with a kiss?) Yes, this eruption progressed as expected.
But in other ways, this is an eruption with surprises. Where do we start!
First, the location. The Reykjanes peninsula is chocker block full of holocene lava fields. The tip of the peninsula is still utter devastation, from eruptions that happened in the 13th century (weather and overgrazing may have helped preventing much recovery). But there is one area that has avoided all eruptions since the ice age: between the thermal regions of Krysuvik and the blue lagoon. And the lava decided to come to the surface right in the middle of the safe zone. why??
Second, the source of the magma. It is melted mantle material, without much (if any) melted crust. It has come from 15 km down, not instantly (there was a dike involved which provided temporary storage) but fast. It was expected that over 800 years of silence, magma would have collected in the crust, at 5 km depth or a bit more until there was enough to begin a new eruption cycle. Eruptions here happen cyclical, after all, with of order 1000 years between phases. Previous cycles indeed produced more evolved magma, indicating a more shallow origin. But instead, this magma came from much deeper.
Third, the stability. The eruption rate seems to have settled at 6 m3/s. You would expect the rate to decrease as the pressure in the feeding chamber decreases. That is not happening, as far as we know. That makes it very hard to know what will happen next. Is there now an open conduit to the mantle, allowing the magma to rise up at a constant rate? Or is it like a bagpipe, where a reservoir is slowly being squeezed out at a constant rate, which may be different from the rate at which magma is added to the reservoir? The answer to this will only come when we know whether the magma composition is or is not evolving. At the moment, the MgO content is measured at 9%, in two separate measurements 4 days apart. But that was a week ago and we do not yet know whether it has changed since.
Fourth, the volatility. If this sounds in contradiction to the previous point, know that this refers to how much gas there is in the eruption. It is not too bad. The tourists, even those uncomfortably close to the lava, are not keeling over from the fumes. (It is not healthy either, I should add.) Yesterdays’s reports suggest that this is because the mantle magma had been melted before, resolidified, and them remelted. The first melt had allowed some gas to escape. When the earlier melt happened is not known, of course. It may have been last century, or it may have a long time ago. It may even come from the origin as subducted ocean floor, with the first melt happening on the spreading rift in the ocean that preceded the Atlantic.
Fifth, what caused the flames seen at various times during the eruption? It very much looked like a candle flame, but what was the fuel? Lava may glow, it does not burn. Options are carbon from the soil, hydrogen from oxidization of iron-hydride, and sulfur burning to sulfate. It is only seen away from the strong fountaining.
How will it continue? The big question is, how long will it last. We will let our readers decide: the choice is yours. To give a useful number, at the current eruption rate, it would take 7 months to get to 0.1 km3, and 6 years to get to 1 km3, so it is related to how large you think this will become.
At some point the lava may spill over into the neighbouring valley. The entrance is out of view for both our cameras. But that is ok as the lava is not yet going there but is still flowing towards the deepest point in the valley, away from the exit. It may be a month before that changes.
The two valleys are called Geldingadalir and Meradalir. As pointed out here, those are horsey names, with the first referring the geldings (castrated) and the second to the mares. Apparently the latter got the better valley, with better grazing. The first valley is no more.
Various videos have been made by our commenters. Here is one from astropgraph99, recommended for those who like their lava fast. I love it.
If you like your lava at leisure, we recommend the timelapse by our Virtual commenter. I love this one too.
And some beautiful images taken by Lisabet, on 23 March.
The results of the poll are
Most votes went to a 6 month duration, with 29% of the votes. The options 1 month, 1 year and longer than 5 years each scored 20%. 5 years got 10%, and 1 week got 1%. Interesting, the people who expect that it will last more than 1 year, tend to go for more than 5 years. But overall, the opinion is that it will last months to years! We can take 6 months as the VC prediction.
Regrettably, two people had to be removed from the voting list as they voted many more times than once. We did allow for multiple voting, but that was in case people could not make up their mind. Not to submit the same vote 10 times or more. If this is you, consider yourself as having been told off and please take a class in Basics of Democracy – one person, one vote!
And of course, volcanoes will completely ignore our voting anyway. But the last we time we took a vote, Reykjanes came out as a high scorer for the next eruption in Iceland. VC commenters have a good track record!