When an Icelandic volcano with a nearly unpronounceable name erupted after 200 years of quiet in March, it was little more than a curiosity. But when it erupted again in April — this time spewing huge clouds of ash as high as 11 kilometers into the stratosphere, quickly choking airways across Europe and costing airlines billions of dollars — it captured the world’s attention. As the ashfall decreased and airlines resumed normal routes this week, the headlines began to fade.