While I generally like the idea of more world events, I think the fact that it's completely random makes it unrealistic. For example, if I were to have my airline based in Muscat, Oman in real life, my chance would be effectively 0 to have my home base shut down by a volcanic eruption (the closest even slightly active volcano being ~2500 km away) . That said, I should be far more prone to political instability, and Kabul is of course far more likely to be shut down by some action rather than a small US regional airport.
Cheers,
Florian