Our excitement was pretty well founded, though. We're all rock-hounds and lava-fiends, and most of us came to study in Iceland at least partially because of this possibility. I realise I'm not exactly selling you on the extreme coolness of volcanologists here, but whatever. When we get a job we have a 1 in 10 chance of it killing us anyway, so we probably don't care that we're uncool. But for those of you who are actually cool, and still care what is going on, I shall sum up the events so far - about 15 hours into the eruption.
It started around New Year, when earthquake activity began to pick up in the area of Eyjafjallajökull. GPS measurements showed that the volcano was literally inflating, too - pressure was building up inside. Data showed that an intrusion event was probably taking place - that is magma, molten rock, is pushed up into the volcano from below. Most intrusions never reach the surface, but were hopeful anyway. An 'acid pulse' in early February caused the groundwater to become acidic due to gases from the magma seeping up through the rock. Despite these signs, chances are it would just be another intrusion - one occurred previously here in summer 2009, and a few times in the decades prior.
A couple of weeks ago, earthquake activity spiked. It literally went off the chart - a huge 'earthquake swarm', thousands of tiny movements, began. Something unusual was going on. Debate within both the scientific and amateur volcanology communities was rife, but as with most things in volcanology, no-one was really sure what was going on.
The earthquake swarm died down a few days ago. It looked like things might be coming to a halt, although the mountain continued to inflate. Then last night, things took a turn for the interesting (if you're a volcanologist, anyway). Low-frequency tremor, which usually means that magma is on the move, began to show up on instrument readings. The earthquakes being measured were getting shallower.
Then, at about midnight, the first report of light being seen coming from the glacier. Apparently, shit just got real. Information came trickling in throughout the (sleepless) night, but come daylight a better picture formed of what was going on. So, as of right now, the latest is that a 1km fissure (crack in the ground) has opened up on the ridge between Eyjafjallajökull and Mýrdalsjökull, which is producing lava flows in both directions away from it. The fissure trends roughly north-south (which is a little unusual, actually), and is (was?) producing a spectacular curtain of lava, plus an ash plume rising into the air. Route 1 was closed past Selfoss last night, presumably to aid in evacuations and until scientists knew what was going on, but now appears to be open all the way to Vik (i.e. as normal). There isn't really any risk of a 'jökulhlaup' (glacier run - glacier meltwater flood) right now.
So what will happen in the future? Well, no one can really predict how long this will last. It could be hours, days, weeks, or months long. The activity along the fissure will probably change from a long curtain of lava into more isolated single vents along the line. The fissure could extend, however, or more could open - there is certainly still possibility for an eruption below Eyjafjallajökull glacier, which could produce a jökulhlaup. It is also worth keeping an eye on Katla - last time Eyjafjallajökull erupted, so did Katla. Katla is also thought to have produced a tiny eruption in 1999 following one of the intrusion events at Eyjafjallajökull. The two volcanoes appear to have a mechanical linkage somewhere below the surface, and so it is definitely worth keeping an eye on that.
But, for now, the eruption continues. Weather is poor, which is hampering attempts to actually see it, but hopefully that will clear. I'll be heading out there tonight for a cursory glance, and again early next week with some luck for a much closer investigation.
Updates will come as I get them (and the chance to write them!). Until then: don't panic, sit back, and enjoy the show!
Grapevine's volcanologist student friend James Ashworth wrote this for us. He is very smart about volcanoes. Expect more from James soon: It is 1am. My phone rings. My friends' phones are all ringing. Emails and Facebook messages are flying around. Why? A volcano is erupting, we are volcanology students, and this is the most exciting thing since... well, since the last time something really exciting happened.