Wednesday, September 3, 2014

Scientists advised to leave Holuhraun

Flokkar: Volcano
The Holuhraun lava eruption (picture: Armann Hoskuldsson)
Geologists working near the Holuhraun eruption north of Vatnajokull have been called back, as increased volcanic tremor has been detected in the vicinity. GPS measurements show that the magma intrusion has increased since the beginning of the current eruption and a rift valley has formed.
Seismometers at the Icelandic Met Office have in recent minutes shown increased low-frequency tremor at stations near the northwest part of Vatnajokull. The Civil Protection Agency has now called everyone back who was near the fissure in Holuhraun, due to concern that the eruption could be getting bigger, or that magma could break the surface at another location. No changes in the eruption have as of yet been confirmed.

According to the conclusions of the latest Scientific Advisory Board of the Civil Protection Agency, posted at noon today, the volume of the dike intrusion from Bardarbunga volcano towards the north has increased since the beginning of the current eruption in the Holuhraun lava field. This is taken to signify that more magma is entering the dike than is being erupted.

This has resulted in a formation of a 0,5 - 1 kilometer wide depression, or rift valley, both north of Dyngjujokull outlet glacier, as well as beneath the glacier itself. Signs of the depression extend about 2 km. into the margin of the glacier. "The increasing thickness of the glacier decreases the visual extent of fracturing associated with the depression, so it is likely that the area extends further beneath Dyngjujökull," says the Advisory Board.

The ongoing eruption in Holuhraun could progress southward under Dyngjujokull, which would lead to a subglacial volcanic activity. The Advisory Board considers this a distinct possibility in light of the GPS, radar and seismic observations. An eruption of that kind would lead to immediate flooding hazard on the floodplains north of Dyngjujokull: a large flood (jokulhlaup) would run down the Jokulsa a Fjollum glacial river towards the north east.

This story, by the Icelandic National Broadcasting Service (RUV), was updated on 3 September 2014, at 15.26 GMT.

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