Grimsvotn Volcano in Iceland’s most active Vatnajokull glacier started to erupt on May 21. The ash plume has reached the height of 20,000 meters. Icelandic volcanologists earlier predicted that the eruption would not cause a major air traffic collapse similar to the one that occurred during the eruption of Eyjafjallajokull Volcano in southern Iceland last spring. However, a total of 500 flights have already been canceled in Europe, most of them in northern England and Scotland.