Large amount of magma accumulated in a week

The subterrainean cavern under the Dyngjujökull glacier, that has been stretching northeast from Bárðarbunga, has now reached out from under the glacier, according to geophysicists at the Icelandic Meteorological Office. There's no sign of the seismic activity receding underneath Dyngjujökull, which has been very strong for the past few days. Sara Barsotti, director of the Volcano Watch at the Icelandic Meteorological Office, believes that there is a large amount of magma underneath the glacier and that readings suggest that an eruption is imminent.

0.27 square kilometers of magma

Sara believes that there's currently 270 million cubic meters of magma underneath the Dyngjujökull glacier. This massive amount of magma is both present in the subterrainean cavern and in the Bárðarbunga caldera. "We're comparing the readings from our GPS devices with the models that we're working with. By comparing data from several sources we've tried to determine how much magma is lying under the glacier. Based on those calculations we believe that the amount of magma, which lies several kilometers beneath the glacier, to be around 0.27 square kilometers, or 270 million cubic meters. That is a very large amount and the activity is still very high."

For comparison, 500 thousand cubic meters have been blasted away in making the new tunnel under Vaðlaheiði north of Akureyri. The estimated magma amount under the Dyngjujökull glacier would fill that tunnel 540 times.

5 times the Hvalfjörður tunnel in one week

Since the seismic activity in Bárðarbunga started, the magma has been flowing into a subterrainean cavern northeast of Bárðarbunga, towards the Dyngjujökull glacier. Sara believes that the cavern is 30 km long and the bearing has been changing from northeast to north by northeast. "We can see that the seismic activity is the greatest around this cavern and has been increasing for the past few days. We're estimating the length of the caverns based on the locations of the earthquakes under the Dyngjujökull glacier."

This cavern has been forming for the past 7 days, allowing the magma to reach as far as it has. The Hvalfjörður tunnel is 5.7 kilometers long by comparison, so the cavern has become almost 5 times as long than that.

The cavern has been steadily growing in length, although a growth spurt was observed over the weekend. Geophysicists believe that it has grown by a few kilometers just over the weekend. "At this point, by looking at the quakes by the north end of the cavern, we believe that it has reached an area from outside of the glacier. That means that now the chance is greater that an eruption will take place in a glacier-free area, which would contain much less ash and cause much less damage than an explosive eruption from underneath a glacier," Sara states.

In her opinion, Sara says that it isn't more likely to erupt now than before. In the end it's all still guesswork.

Likely to end with an eruption

The activity in the area has been going on now for over a week. The strength has varied, but the seismic activity has picked up in the past few days. The Icelandic Meteorological Office registers thousands of earthquakes every day. Sara believes that the series of events that we're witnessing will eventually result in an eruption.

"It wouldn't surprise me. I doubt that it'll recede without an eruption. But it's still a possibility that can't be ruled out. But we can't determine the time factor, we don't know if it'll take hours, days, weeks or even months."