A video from Youtube, by Gamers on Fire: Grimsvotn eruption in Iceland in May of 2011. It emitted more ash than the famous 2010 eruption of Eyjafjallajokull (which is not inside the boundaries of Vatnajokull National Park). Right in the beginning, this eruption was considerably more powerful than the Eyjafjallajokull eruption the year before. At its peak, the outflow of volcanic material was estimated at 10,000 tonnes per second. But on the third day it had reduced down to being much smaller. Never the less, it did have an effect on international air travel, but that effect lasted much shorter. Seven days after starting, the eruption was vaning out.