i have a feeling we're in the beginning stages of katla's eruption.
[link to hraun.vedur.is
the blue spikes you see on that chart are harmonics, and they are escalating, I believe.
I put an image together to show you what I mean..
[link to i43.tinypic.com
the black vertical lines are showing the peaks and troughs of the 0.5 to 1 hertz signal.
notice the surprisingly calm, downward signal on the blue and green lines this past 2 days?
why I think this may be the start of the eruption phase is i saved ANOTHER pic of this link back on february 28, because I noticed a steady rise in the tremor..
[link to i40.tinypic.com
notice the start date on BOTH images? they're keeping 15th of February as a start date. do THEY think it's started?
whatever. let's keep an eye on this.