1. Seismic activity started at the end of 2009 and gradually in-
creased in intensity until on 20 March 2010, a small eruption
started rated as a 1 on the Volcanic Explosivity Index.
Beginning on 14 April 2010, the eruption entered a second
phase and created an ash cloud that led to the closure of most
of the European IFR airspace from 15 until 20 April 2010. Con-
sequently, a very high proportion of flights within, to, and from
Europe were cancelled, creating the highest level of air travel
disruption since the Second World War. -wikipedia
2010 Volcanic Eruptions of Eyjafjallajökull

2. Seismic activity started at the end of 2009 and gradually in-
creased in intensity until on 20 March 2010, a small eruption
started rated as a 1 on the Volcanic Explosivity Index.
Beginning on 14 April 2010, the eruption entered a second
phase and created an ash cloud that led to the closure of most
of the European IFR airspace from 15 until 20 April 2010. Con-
sequently, a very high proportion of flights within, to, and from
Europe were cancelled, creating the highest level of air travel
disruption since the Second World War. -wikipedia
2010 Volcanic Eruptions of Eyjafjallajökull