The ash cloud from a volcano in Iceland that has wreaked havoc on European air traffic has significantly diminished, but eruptions continue, experts said Tuesday. Meanwhile, US vulcanologist John C. Eichelberger said the pathways put in place in several countries to gradually resume flights will be 'very difficult to manage' as the cloud keep moving. He said most of the ash is like "little particles of glass" that melt and coat planes' turbine engines, making passing through the cloud very hazardous.Duration: 02:09