England was harder struck compared to the continental Europe not only because of its proximity to Iceland, but also due to its geological isolation. The U.K. is an island nation. The logistics depend much on the air, especially in the shorter time scale. In the continent people are able to use other means of transportation, albeit taking much longer time. Something is better than nothing. An island nation, when deprived of air, can go into a state of despair. Much thanks thus are due to the channel tunnel, without the existence of which the U.K. would have been more severely cut.
When I think the state surrounding my own nation, the island vulnerability is clear. If Japan loses its airspace, it would be virtually cut off from the outside world, especially in the shorter time scale.
The largest volcano, Mt. Fuji, has last erupted in 1707. Theoretically, it can erupt at any time again, letting out a huge amount of ash like the Icelandic volcano did this time. That could well lead to the loss of airspace in metropolitan Tokyo, judging from the events in the past days.
The nation clearly needs a contingency plan in case eruptions (not necessarily limited to Mt. Fuji) happen. Meanwhile, while I return to normal from the ashes, I brush up my cognitive processes so that my world model would better reflect the inherent unpredictability of the world that we inhabit.
You never know what tomorrow will bring.

Mount Fuji as depicted in a famous Ukiyoe print by Hokusai.




