Though not as famous as Eyjafjallajökull, Katla or Laki, when Grímsvötn pops it pops.
From Iceland Monitor, September 16:
There is every indication that the Grímsvötn volcanic system under the ice cap of Vatnajökull glacier is ready to erupt, according to Benedikt Gunnar Ófeigsson, deformation scientist at the Icelandic Met Office, mbl.is reports. Grímsvötn is the most active volcanic system in Iceland in Holocene time, that is, for the past 11,700 years.
Data obtained through a GPS station on top of the glacier show that the ice cap over Grímsvötn continues to inflate. “The ice cap inflates, mainly because meltwater flows into the lakes,” Benedikt explains.
A second GPS station nearby, on a cliff in Grímsfjall mountain, southeast of Grímsvötn, has registered inflation as well. “That station shows increased inflation, which is due to magma accumulation,” Benedikt states....
....MUCH MORE
Some of our previous volcano links (there are hundreds):
Listicles, Financial Times style!
Risk: "Are we ready for the next volcanic catastrophe?"
"Is a super-volcano just 390 miles from London about to erupt?"
Laki: How A Volcano Swallowed Europe
"It was the last wish of the Icelandic economy that its ashes be spread over Europe"
Here's the BBC's Guide to Icelandic Pronunciation. Pity the poor newsreaders.