Eyjafjallajökull Eruption – UPDATE 22 April

Volcanic tremors continue unabated, Eyjafjallajökull ash plume stays low

The explosive activity at Eyjafjallajökull is less vigorous, with only one of two main craters in the summit caldera remaining active.

Webcam views of Eyjafjallajökull eruption recorded at 15:23UTC on April 22, 2010 – Click images to enlarge

Hvolsvelli View

Thórólfsfelli (Þórólfsfelli) View

“Eruption rate is inferred to have declined over last few days and now be an order of magnitude smaller than during the initial 72 hours of the eruption. Present eruption rate is estimated to less than 30 m3/s of magma, or 75 tonnes/s , with a large uncertainty.” The Institute of Earth Science Nordic Volcanological Center said.

The eruptive style was reported as: “Phreatomatic explosive activity” with “lava spatter” at the summit craters, with the plume height reaching 3,000 m asl.

Seismic tremor showed some fluctuations but remained mostly stable, said the Icelandic Meteorological Office. “Tremor is not decreasing and does not reflect the decline as inferred from the eruption rate.”

Freeze frame from a video of Eyjafjallajökull Eruption shot by Icelandic Coast Guard.

The Institute of Earth Science Nordic Volcanological Center said:

Tephra dispersal: local towards the south

Meltwater: minor, but what is melted flows down into Markarfljót, no signs of water accumulation in craters

GPS-measurements: indicate continuing small pressure decrease under the volcano at a similar rate.

Composition of erupted material: Samples collected April 19 show same composition as early in the explosive phase, but fluorine content is higher. Samples collected 19 April have 850 mg/kg (initially it was 25-35 mg/kg). This is due to the change in eruptive style – tephra is now not washed to the same extent by water in the eruptive plume.

Amount of erupted material: Uncertain but on the order of 100 millon cubic meters. Tephra next to craters is 20-30 m thick.

Iceland’s Civil Protection Office confirmed that the ash emissions had been considerably reduced. “The volcanic cloud is quite low and not visible on radars. The ash is not expected to reach an altitude of 20.000 feet (6 – 7 km) for the nex few days. The ashes will continue falling on the area south and south-east of the glacier today, yet the wind will turn and blow from the north-easterly today, and the ashes will start falling to the south-west tonight. The wind is expected to be mild. That, and a lessened ash emission, will cause the ashes to fall near the eruption site. There is no cause to believe that the ashes will fall on the south-western regions of Iceland.”

Relate Links:

• The Next Icelandic Volcano Likely to Erupt
• Iceland’s Bárdarbunga May Be Erupting
• Eyjafjallajökull Eruption – UPDATE 21 April
• Eyjafjallajökull Eruption Links Page

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