Stupidly neglected to include 'volcanic ash cloud causing economic collapse' from my end-of-the-world scenarios. Please consider it added.
Also, Iceland was just picking up some much needed dollars from the tourist market and so a volcano happens so that people can't fly there to spend spend spend. What has the universe got against Iceland? All they have is colourful knitted sweaters, epic poetry and rugged scenery, give them a break.