The end of the Australian TV series Neighbours (which I to my embarrassment never watched) has created room for new home entertainment series. Iceland has stepped into the breech, and has created a serial volcanic eruption. We are now on series II of the Fagradalsfjall fires, just in time for the empty summer holiday schedule. We may find out what happened to that lava surfboard that went missing from the garage of cone number 31 (I am guessing here what a typical Australian plot line might be), or whether that mysterious
idiot tourist who climbed an actively erupting cone in series I and barely survived, gives death another chance.
As we are admiring the lava fountains, it can be hard to see what is actually happening. With such a new and sudden eruption, it takes time to understand the details.
The eruption is viewable from the hills around the fissure, safe from the lava but at risk of poor visibility and lack of breathing opportunity if you find yourself downwind. It is important to check the IMO reports which will include the safety recommendation. If they say don’t go, best to listen. In Iceland even in summer the weather can change very fast. So can the eruption, although at the moment the risk of large explosions is small. But in general, this seems to be a tourist-friendly eruption.
Here is an interview with a very excited person who found herself in the right place at the right time.
Acme remains the best site for the eruption viewing. The site https://eruption.acme.to collates streams from the main cameras. They are located around the eruption site, so if one is obscured by the fumes, one of the others may have a clear view.
The fissure opened up on the side of a hill at the edge of one the lobes of last year’s eruption. Interestingly, this location showed few earthquakes in the swarm preceding the eruption: those were mainly further east and north. It is however on the line of the intrusion from last December when there was another swarm. That did not end in an eruption (to many people’s disappointment) but it apparently set the trigger for this time. To be fair, an August eruption is far better than a December one in Iceland, when daylight becomes a rarity. The weather will deteriorate later in the year: if you are a keen lava viewer, it may be best to go early.
There were questions about the state of the old lava field. It is a year since that eruption tapered down into extinction. In a year, a few meter of the surface of the lava lake will have solidified. Underneath there will still be a mix of liquid and solid material. Some of the lava is 100 meters deep, and in Meradalir the depth is 50 meters. Expect plenty of lava sitting underneath the crust.
The fissure opened at 13:06 yesterday. The earthquake swarm abated sharply, even 10-20 km away along the Reykjanes fault. This shows that the cause of the swarm was the pressure exerted by the dike. Magma pockets build up around 7km deep along the roughly east-west Reykjanes fault zone. Dikes are thrown up from there running north-northeast to south-southwest, reaching perhaps 10 km (about the distance to Keilir). (Much deeper dikes can also form, at 20km depth, and these can reach much much further but do not reach the surface.) The earthquakes had followed several old fissure lines, and with old we are talking ice age and earlier. That is not where the magma was. My feeling is that these ancient fissures are sitting above equally ancient dikes. The plane of contact between the intruded ancient dike (rock-hard basalt, thoroughly cooled down) and the surrounding rock remains a weakness, and the pressure caused these weakness to break. Thus the purely tectonic events. In the mean time the magma crept upwards very quietly. There was very weak occasional tremor on the seismographs, but not easy to notice. The new magma had arrived on Saturday, evidence by weak earthquakes at depth of 10 km. The new dike traced a region between Keilir and the north end of Fagradalsfjall. The eruption occured at the southern end of that dike. It is not clear whether it used the rift that had been created 7 months earlier but my guess is that it did.
The fissure that opened was about 300 meters long. It has contracted slightly since, possible because the southern end has been covered in lava. Eruption rates are reported at 30 m3/s. For comparison, the eruption last year started out at perhaps 5m3/s and later increased to 10-12m3/s. We are looking at a faster rate. There are various possible explanations. The eruption rate depends on pressure, size of the exit hole, and (yes, Jesper), viscosity. This is probably fresher magma at least compared to the initial phase of last year’s eruption, and the exit is wider as indicated by the fact that the fountain are not that high at the moment. There is quite a bit of gas coming out, but for the numbers we have to wait for IMO.
Here is the map created by commenter Philip Daniels with the approximate location, together with an image of the early fissure.
The second map is the model already created for the public (credit: Icelandic Institute Of Natural History).
What will happen next? The lava is being injected in a depression, caught between the low shield of Thrainskjoldur to the north and the new Fagradalshraun to the south. Initially the flow went north, filling up the depression. During the night it began to flow over the lava to the south. It will need to add perhaps 20 meters depth before escaping the depression. That may take a few days. The most likely route is south and east, ending up in what is left of Meradalir. But lava can direct itself and the northern route is not impossible. The fissure is likely to contract further, and eventually (if it lasts that long) is likely create a single cone, I guess near the north end of the current fissure. It may also cease, and break through in a different place nearby, as happened last year. How long the eruption will last is anyone’s guess. Given the higher eruption rate, 1-2 months would seem plausible but it could well be much shorter or much longer! (This is not much of a help but predictions are best made in hindsight.)
In the mean time, enjoy the view! Drone footage is not yet available but can’t be far off. For your enjoyment, here is the timelapse of the first 24 hours posted by Virtual. Note the flocking behaviour of the tourists in the background – once one gets close to the lava, the flock follows.
And Gutntog is of course on the ball, day and night
And his report of moss fires, on far side of the old lava field, apparently started by overnight sparks from the lava fountains being blown here
Albert (holding the VC fort and dungeon while the other dragons are on poorly times holidays. I should ask for a raise.)