Predicting such things is quite tricky. The problem is that the eruptive history of each major volcanic spot is fairly scattershot and patchy, whether it is a mountain or more of a fissure. Most eruptions that took place more than 1,000 years ago have a very poorly preserved geological record.
Ultimately, this means that it’s genuinely difficult to estimate recurrence intervals for any activity in Iceland, including the appearance of huge ash plumes. Still, a rough estimate is better than none at all, and it’s becoming increasingly clear to volcanologists which volcanoes in particularly we should keep an eye on.
Katla is seen as an especially dangerous one, and it has been showing unusual, if not necessarily worrying, seismic activity as of late. Katla is known for its historically violent subglacial eruptions, the types that produce not just sudden glacial meltwater floods called “jökulhlaups” but enormous ash plumes that can last for days.
Hekla, famous more some truly devastating explosions, is nicknamed the “Gateway to Hell” by Icelanders. There are plenty of articles out there speculating on its imminent eruption – it is “six years overdue,” based on its recent history – but honestly, it’s as likely to erupt today as it is in a decade or so.
So really all anyone can do is constantly be on alert for such an event, and airlines must be ready to ground all planes at the drop of a hat. Judging by the way they handled Eyjafjallajökull, then, we can all rest easy – particularly if you’re stranded somewhere rather beautiful the next time it happens.
Eyjafjallajökull, pictured just as the eruption sequence began in April 2010. Max Haase/Wikimedia Commons; CC BY-SA 3.0