probably nobody wants to know any of this but I am going to tell you anyway
First thing that you can see, is that this is a small eruption (I know it doesn't look like it, but it's actually quite small). This first phase is throat clearing, powered by a lot of gas, resulting in a high degree of fragmentation. The gas in the magma expands as it gets close to the surface and blasts the magma apart, resulting in a lot of fine ash. This hot ash sucks in a lot of ambient air, heats it and that's why you get those billowing clouds. The rise of the ash is driven primarily by convection, as you can see from their shape and not by powerful jetting out of the vent. You can also see it is a small eruption because the column only reaches up to about 10 km before it reaches neutral buoyancy when it fans out. All the heavier ash particles start raining down on the countryside and the lighter stuff will waft away to wherever the wind takes it before also falling out.
Overnight the eruption progressed into lava fountaining, which is also powered by a lot gas but there is no longer enough of it to result in such fine fragmentation. In other words you get lapilli and larger clasts getting expelled violently from the vent, which rain down on the slopes of the mountain. There is less fine ash involved. This is a typical evolution of a small eruption as the first magma will be more gas enriched. Slowly the eruption will wane as the gas content falls until it doesn't have enough oomph to make it out of the vent and the thing goes back to sleep.
So what's next: Most likely it will continue to fountain for a few days until it falls back to sleep. However, any movement in a magma system can disturb its equilibrium. It is possible this is just the first sign of a larger eruption and this throat clearing might pave the way for much larger quantities of fresh magma to migrate from depth to the surface. If this fresh magma reaches a point where the pressure is no longer high enough to keep its gas in solution, you can get a much larger eruption happening. Most of the large eruptions I know of, like Pinatubo started of with small eruptions like this. BTW this is not the first one at Calbuco either. Calbuco has had numerous such eruptions recently so it bears keeping an eye on. But this scenario is much less likely than the first one, i.e. the most likely scenario is that it will give us some nice pics, get progressively less violent, finally extrude some thick lava in a dome and shut down.
What's noteworthy about it? This is the second time we have had an andesitic / rhyolitic eruption occur with virtually no warning, which is not a good thing. These volcanoes are the more explosive ones and we haven't seen many of them erupt in the last 100 years. If they all go off without much warning the authorities are not going to have much time to evacuate people. Chaiten just down the road from Calbuco was the other one. The nice Hawaii type / Icelandic type eruptions usually give us loads of warning, kind of like a fire cracker where you keep wondering if the fuse has gone out. Calbuco type volcanos on the other hand seem to explode in the box before you even light the match.
A friend who worked at our coffeehouse when she was in college is in Chile now; her boyfriend had a flight to Puerto Montt cancelled yesterday... he was a little upset until he found out why...
ha, imagine being on a flight like that:
"And ladies and gentlemen, to our right we have the lovely graceful cone of - holy shit!" Edit, btw, as long as the pilot doesn't decide to actually fly through the ash cloud you should be fine. You'd have to be pretty unlucky to get hit by the shock wave but I guess that's also a possibility. Never heard of it happening though. Would be a bit like sitting on enola gay I guess.