The eruption in Grimsvotn seems to be dwindling

The eruption in Grimsvotn has steadily grown smaller since yesterday. The volcanic column currently reaches an altitude of three to five kilometres, and the output of ash is considerably smaller. There are still very strong northerly winds in the area blowing the ash to the south. The winds will go down later today, according to the Icelandic Meteorological Office.

About 100 tons of volcanic materials erupt per second from the volcano in Grimsvotn. Yesterday it was about 1,000 tons per second, so the output of volcanic materials has greatly decreased. As a comparison the output was ten to twenty thousand tons per second when the eruption peaked last Sunday. Volcanic tremors have, however, stayed unchanged.

According to the Meteorological Office there have been no deep tremors and no lightning detected since midday yesterday. The eruption column now reaches three to five kilometres compared to eight to ten kilometres yesterday. There are strong northerly winds in the area, blowing the ash to the south and causing much ash drift in the area. The wind is, however, supposed to go down this evening.

This is an explosive eruption accompanied by great amounts of ash. The ice around the crater melts and water in the subglacial lake at Grimsvotn causes the volcanic materials to explode, creating this huge volume of ash. Magnus Tumi Gudmundsson, geophysicist, says it is unlikely that the crater will become dry during this eruption.

"There is enough water in the glacier and the water in the Grimsvotn lake controls the water level. While the eruption is this strong the rims around the crater do not accumulate. The only build-up is on the glacier around the volcano, so the water has clear access to the crater. We have no examples of anything else in Grimsvotn," says Gudmundsson.

He says that it is, therefore, likely that for as long as the eruption lasts it will stay an ash eruption.

"We have to be prepared, and we cannot rule out there will be a lava flow, but it is not likely to happen as long as the eruption is relatively powerful," he says.