Here's a little help on that -0.6 [or -0,6 across the pond] number. It is not an earthquake magnitude. It is actually a measure of whether the volcano that might erupt (Bardadur--sp?) is either swelling up (+) or deflating down (-).
The high, conical (more or less) volcano (capped with a lot of ice) acts like a municipal water tower. It pressurizes the underground caverns and tunnels through which the melted rock flows upward. Typically at a certain age it is more common for the melted rock to find a weakness on the flanks of the central volcano and then discharge at a lower elevation some distance from the top of the volcano. At the moment the discharge is some miles to the NNE through a long passage (or several) to area where a great many old fissures lead to the local surface. This area is quietly steaming right now.
This outlet is being fed by a drop in the melted rock level within the higher volcano itself. That causes the flank of the volcano rim to move inward, and also tilt inward. There are several ways this can be measured, either horizontal movement inward or by an inward tilt, depending on the instruments available and placeable. I am not totally sure what this method here is, but let's just say that in this case two opposite points on the rim are now -0.6 centimeter closer to each other in the last 24 hrs. It will go both ways, and after a while a trend can be seen. The trend can reverse as well. If it's tilt, the -0.6 is some measure of an angle (seconds of arc?).
The melted rock contains water, which will flash to steam if enough pressure is removed. Meantime, the steam pressure of the heated water both assists the quartz fraction of the rock to melt and propels the hot slurry through the underground tunnels (sizes in the usual sense of tunnel as we use it). The earthquakes are lurches as the heavy melted rock moves, for the most part, altho their exact nature is not totally understood.
The Icelandic Meteorologic Office has some papers and reports on these subjects on their user-friendly website, in English as well as Icelandic. The key thing here for aircraft, however, is that the Icelanders really watch this stuff, and since 2010, appear also to have upgraded their ability to quickly detect conditions which would be a danger. Hawaii Volcanoes Observatory is also another source of info, altho their excellent commentator has retired (it was a lot of work, some of which he donated).
As for trouble reading all the jargon used, don't feel bad. I was once a geologist, and I know what you're saying. Like the 0.6-- I didn't worry if it was millimeters or meters or angles. It's only whether it's plus or minus and what that means that matters. So long as you've seen it all before, it's ok... ...if not, run
