That was quite a day. After the fissure had opened early in the night, and everyone was scrambling for a view that was a bit more than a red reflection off the clouds, in the day time everything became clear. A camera was put up on just the right place, courtesy of RUV. Not even HVO managed to do it this well. The setup team even was on camera themselves, whilst they were working. The highlight was when one of the three went to his knees, it turns out not to pray he got it right, but in order to take a lava-selfie. It is almost the same thing, I guess.
We had (and have) a brilliant view of the eruption, the flowing lava, the intermittent snow, the helicopters and the small plane (presumably sampling the gas emissions), and very quickly the tourists. At one point a large group of people was standing around and doing something right at the edge of the approaching lava. They had to retreat as the lava advanced but kept doing their rituals. It appears this was a group of archeologists trying to rescue a pre-christian burial site. To ‘rescue’ means ‘to document’ to an archeologist. The burial site would have dated from the previous pghase of Reykjnes eruptions, before the year 1000. This valley was never affected but the eruptions. Now, finally, the luck of the buried people has run out. See https://twitter.com/astro_graph/status/1373596762565455875
There is a nice timelapse made by commenter astrograph99. The archeologists can be seen about 1 minute in.
And here is a lava layout courtesy of commenter chrnesset.
Other things we learned yesterday is Motsfo likes popcorn with her lava, that Alaska is cold and the Faroer is not, and that half of Reykjavik including commenters are planning to go to eruption today. Lava to an Icelander is honey to a bee. This is about as friendly an eruption as you can get, with lava that can’t get anywhere and stays in a valley and ridges provide excellent viewpoints. The only problem is that it involves a long hike. The weather also is not particularly viewing friendly today, bit this is Iceland after all. You have to accept whatever weather is thrown at you.
From the map above, it seems that the lava as of last night covered some 0.1km2. Assuming an average thickness of 10 meters, gives an average eruption rate of (very roughly) 15 m3/s. This is not particularly high and it adds to the touristic quality of the eruption. A much faster eruption would be much more dangerous. (The eruption rate normally decreases after the first burst, so by now the rate may be quite a bit lower.)
The fluidity of the lava is hard to judge from video frames. At times it flows quite fast, at other times it seems more sluggish. My impression is that the magma was a bit stale, perhaps already a bit cooled during the weeks of storage in the dike. But that impression should be taken with a big grain of salt. Of course the top stuff is erupted first, and that may be the oldest which was deposited first. If this continues for a while (that is an if), the younger and hotter lava may make its way to the surface later. Wait and see.
There were perhaps 6 or 7 vents during the first day of eruption. This is common in rift eruptions. All are building spatter cones (which are prone to collapse. be careful!). Over time, you would expect that one cone will become dominant and starve the other vents of magma. At the moment, three of the vents are active.
The wind is blowing the gas towards Reykjavik: https://dispersion.vedur.is/map.html. IMO writes that “gas pollution is not expected to cause much discomfort for people except close up to the source of the eruption.” They do have a stern warning: “The area of the eruption is considered very dangerous – the eruption site can change without notice and put people at risk unexpectedly.” We recommend that people follow all advice from the local authorities (which we are not!). If you go viewing, be well prepared (don’t expect a paved path – the only pavement is hot lava), don’t expect water on tap, and stay upwind from the gas clouds. And remember White Island.
A notable change since yesterday is that there are still earthquakes in this location, but they are now deeper, at 4-6 km. The shallow earthquakes have ceased.
How much magma is there? The dike was reported to be 10 km long, 5 km deep and 1 meter wide. That makes it about 0.05 km3 (and not 0.5 as was here initially..). Much of that is not accessible to this location: magma at the tip will not easily flow back to the centre. If there is no magma re-supply, it is unlikely more than a fraction of this will erupt. However, if the entire dike erupts, at the estimated rate, that could keep the eruption going for a month. (This has been updated to fix a catastrophic math error, pointed out in the comments. )
So it is back to wait-and-see! But the seeing is mesmerising. Or even magmarising.