It has begun.
They just interrupted a concert to announce that a lava eruption has begun under Dyngjujökull. It´s typical for volcanoes in this system to begin with small lava eruptions, and especially under the glacier, as it has to break through first before there can be an ash plume. No sign yet of a breakthrough, there's 150-400 meters of ice over it. The location not far from the edge of the glacier should hopefully limit the size of the jökulhlaup (volcanic glacial outburst flood), although it's still a major risk to all three bridges connecting northeast Iceland with north Iceland. Scientists are en route. After calming down for a while, this morning the magma intrusion shot rapidly northward, described as as if the cork just popped. There's a failure in the communications for one of their important flow meters, so they have no realtime data from it. The seismometers are going bonkers, and there's a massive spike in tremor measurements. The aviation warning map has set it to red, its highest alert.
Again, to reiterate the key points:
1) Big dangerous volcano that deserves close attention.
2) Eruption has begin
3) It's currently a small subglacial lava eruption, which is typical for these systems. It will most likely change with time.
4) No data yet on a potential jökulhlaup, but it's likely. No clue whether it'll take out the bridges.
I'll update more this evening after I get back from Menningarnótt. Sorry for the rushed entry!