According to what I’ve read, Katla blows her cork after the one most of us cannot pronounce does.
She has the last 3 times, and followed the smaller one just shortly afterwards, but I’ve never read just what “shortly” means in this case. Days? Weeks? Months?
I just call it Eyja. Y’know, like Lielu from The Fifth Element.
Within a year as far as i can tell from googling volcano websites. But, realize that the "last 3 times" goes all the way back to the year 900. The unpronouncable volcano doesn't blow very often.
Katla blows about every 50 to 80 years. The last major eruption was back in 1918. There was possibly a very tiny eruption of katla that did not even break through the ice in the 1950s and again in 1999. But in 1918, the last time it had a major eruption, there was essentially no air travel unless you want to count hot air balloons, so nobody knows how bad it might be. It's described on most sites as "ten times bigger than Eyjafja(etc). Most vulcanologists think Katla is overdue for a major eruption, which makes the tie-in with Eyjafja(etc) pretty disconcerting. The smart money would be on a major eruption of Katla within the next 12 months or so.
For practical purposes, this means 2 things. (1) its probably a really bad idea to travel to europe for the next year or so. You might easily be stranded there for an unknown period of time. (2) the investment play would be long term put options on european travel industry companies like airlines or major resorts.
Mebbe I can help...
Eye Yaff Yalla Yokull