On 21 May 2011 at 19:25 UTC, an eruption began, with 12 km (7.5 mi) high plumes accompanied by multiple earthquakes. The ash cloud from the eruption rose to 20km/12 miles, and is so far 10 times larger than the 2004 eruption, and the strongest in Grímsvötn for 100 years.
en.wikipedia.org/wiki/Gr%C3%ADmsvötn 