Friday, 5 September 2014

Latest news - Iceland's Bárðarbunga volcano

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Bárðarbunga is a large central vent volcano lying underneath Iceland's 500-m thick Vatnajokull glacier in the centre of the country. It is located at the junction between the eastern and northern volcanic rift zones in the area close to where some scientists consider is the present-day location of the mantle hotspot beneath Iceland. The complex rifting means that there are probably sub-surface magmatic connections to both the Grimsvotn and Askja volcanoes.
Bárðarbunga has had about 300-400 eruptions during the past 10,000 years including 23 eruptions in historic times with the last one having occurred in 1910. Worryingly, it produced the largest known lava flow during the past 10,000 years on earth (more than 21 cubic kilometers of volume). The lava was erupted from the Veidivötn fissure system and travelled more than 100 km to the south coast.
Since the beginning of August the  Icelandic Meteorological Office (IMO) has been keeping a close eye on activities in the Bárðarbunga area. They were particularly concerned that there may be a major sub-glacial eruption (jökulhlaup) that had
the potential to repeat the historic eruption referred to above.
Recent activity:-
Initially, there were small ash eruptions from a point close to the old Bárðarbunga vent and then major magma movement was detected along a 6 km rift that has taken the activity away from the glacier and towards the Askja volcano. Meanwhile, large circular depressions in the glacier have been detected, indicating that there is still some activity further to the south.
On August 30th and 31st a classic lava curtain eruption began along a section of the rift where a shallow dyke had been emplaced. Basaltic lava and a little tephra has been erupted, well away from the glacier.
So far there has been no major disruption to aviation and the eruption remains of the effusive lava type.
Seismic events:-
Several seismic events have occurred around the Bárðarbunga caldera rim of magnitudes around 4.5.
If this goes according to the pattern of many previous Icelandic eruptions, one of the following may occur:-
• eruption continues at the present level for a month or so
• the eruption dies down and then ceases with the basalt cooling
• the eruption becomes concentrated on a single point which could be Askja or another location
• none of the above scenarios may apply!

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