It is now three days after the start of the Reykjanes eruption. What is the state?
The flow field is slowly expanding, and is thickening. It remains a touristy eruption, but tourism is up and down. Initially it was discouraged as events were still unfolding. On Sunday they came in large groups; our local correspondent commented that half of Reykjavik wanted to come. That caused some problems. The ridge next to the cones were popular, but evacuated around mid-day. In hindsight just in time as a little later a significant collapse of the cone pushed a lava surge in that direction. A video of the event shows it nicely. The ridge is now close to being surrounded by the lava.
Some people got in trouble last night when the weather deteriorated and they got lost and cold on the 2-hour cross-country walk back. Today the weather was atrocious, and measurements indicated that gas concentrations close up to the lava reached dangerous levels – presumably that was true the previous day as well.
Lisabet, our local correspondent, send some very impressive photos and made many commenters feeling very envious. Click on the image for the full resolution.
The eruption is now concentrated in three cones. The dominant one had the collapse (and may have more to come). The smaller, middle one showed a mystery last night: in addition to the spatter, flames came from the top. They moved in the air exactly like real flames. But it is very unclear what caused it. Apparently this has also been seen in Kilauea. The most plausible combustant would be carbon, picked up from peat on the surface underneath the cone. But this is speculation.
Here is a video showing the f=mysterious flames at Kilauea.
The story about the groups of archeologist doing emergency excavation was overstated. There was only one, trying to do a very quick site survey before it was overrun by lava.
There are now some reports coming out on magma composition, as mentioned in the comments. The magma is a bit less gaseous than Holuhraun was. It originated from a magma chamber 17-20 kilometers below the surface. It may have spend considerable time there (one may guess centuries). This would explain why the lava is a bit blocky, as it will have become more viscous during long-term storage.
We estimated that over the first 24 hour, the eruption rate was roughly 15 m3/s. Today, numbers of 5-10 m3/s were reported. The eruption may have decreased a bit since the initial flush. But it is still going strong, without any indication that it would end soon.
The eruption rate can tell us a bit about how wide the feeder pipe of the eruption is. The magma is pushed up by two effects: buoyancy, and overpressure. The buoyance comes from the fact that the liquid magma is slightly less dense than the solid basalt of the crust. If we assume that this is the only effect, there is a simple equation which sets the flow rate. For a cylindrical conduit, it depends on the radius R, the viscosity, and the difference in density. Putting in the numbers, and assuming a difference in density of 100 kg/m3 and a viscosity of 104 Pa s, gives that a flow rate of 10 m3/s corresponds to a conduit radius of about 3 meters.
If it is overpressure, the numbers change. A rift suggest a dike rather than a spherical conduit. The picture shows the model: a magma chamber at 5 km depth, a flattened conduit going to 1 km depth, and a cylindric conduit for the final kilometer. For a magma overpressure of 20 Mpa, the dike could have a cross section of 500 m2 ( for instance 500 meter long, 1 meter wide), and the conduit t the surface a radius of 15 meters. This also gives a flow rate of 10 m3/s. This model is rather plausible. It allows for several conduits, each feeding a cone. Models of such a situation suggest the possibility of varying eruption rates over a period of weeks to months. (Costa et al., https://doi.org/10.1029/2006GL027466)
We do not expect a sudden end to the eruption in the next day or two (although this can never be excluded!). We are looking forward to days of envious staring at the camera. Reports that a shield may build should be taken with caution. That hasn’t happened here since the early holocene, and a more typical, smaller eruption is more likely. Whatever happens, like Holuhraun, we will learn a lot about how volcanoes work.
And a final point. Today our current VC site reached 4 million views, something the VC team is quite proud of. We try to provide a forum where volcano science and volcano experience can meet. We are glad that VC is appreciated.
The average website has a carbon footprint of 1.8 gm of CO2 per view. That means that VC is responsible for 7200 kg of CO2. How does that compare with the volcanoes that we study? Read
There is one volcano that produced less net CO2 than VC: Eyjafjallajokull, now exactly 10 years ago. It managed to offset all its CO2 by causing the flight ban. Icelandic volcanoes never cease to amaze.