{"id":1419,"date":"2014-12-28T13:28:28","date_gmt":"2014-12-28T13:28:28","guid":{"rendered":"http:\/\/all-geo.org\/volcan01010\/?p=1419"},"modified":"2014-12-28T13:48:59","modified_gmt":"2014-12-28T13:48:59","slug":"holuhraun-fieldwork-videos","status":"publish","type":"post","link":"https:\/\/all-geo.org\/volcan01010\/2014\/12\/holuhraun-fieldwork-videos\/","title":{"rendered":"Holuhraun fieldwork videos"},"content":{"rendered":"

When we sing Auld Lang Syne and raise a glass to 2015 on Wednesday, the eruption of B\u00e1r\u00f0arbunga volcanic system, Iceland, will have been going for four straight months. In that time, the eruption has covered over 80 km2<\/sup> (1.3 Manhattan islands) of sandy outwash plain at Holuhraun, to the north of the Vatnaj\u00f6kull glacier, with a jumble of jagged black basaltic rock ranging in thickness from the height of a car to more than the height of a house.<\/p>\n

By all measures, the eruption is slowing. The seismic energy released by earthquakes in the dyke (underground crack) that carries the magma to the surface is one ten-thousandth of what it was<\/a> as the dyke was forming. The subsidence of B\u00e1r\u00f0arbunga caldera, probably caused by draining of magma away from the volcano and out to feed the lava, dropped from over 80 cm per day to less than 25 cm per day; the accompanying magnitude 5 or larger earthquakes there, which used to happen every day<\/a>, can now be a week apart or more. Satellite measurements of heat flux<\/a> show a decline from over 20 gigawatts in early September (to put this amount of energy in context, the average UK electricity demand<\/a> in 2012 was 36 gigawatts), to fewer than 5 gigawatts by the end of November.<\/p>\n

This doesn’t mean that the eruption will stop soon. Like the weakening spray from an aerosol can, the eruption rate declines exponentially.\u00a0 The lower the flow, the more slowly it declines.\u00a0 SSKKKOOOOSSSSSSHHHHH ..ssshhhssshhhssshhhssshhhssss ..sssssssss..ssssss ….sssss……sssss……sss! Icelandic scientists have predicted that it has ‘at least some months’<\/a> more to go. From initial rates of up to 1,000 m3<\/sup>\/s, an average of 200 m3<\/sup>\/s through September, the eruption rate in November<\/a> was less than 100 m3<\/sup>\/s.\u00a0 This still corresponds to a healthy river of lava; the mean flow of the Thames<\/a> through London is around 60 m3<\/sup>\/s.\u00a0 Effusion rates of less than 5 m3<\/sup>\/s are typical of recent Hawaiian eruptions.<\/p>\n

An interesting development is that the lava is now flowing through covered tubes. These are better insulated than open channels so the lava cools much more slowly (as little as 1\u00b0C per kilometre) and can travel further. I’m personally hoping that this means that the lava will extend further to the northeast, reaching Va\u00f0alda and blocking the Svart\u00e1 river that flows into J\u00f6kuls\u00e1 \u00e1 Fj\u00f6llum from the northwest (see map) to create a new lake.<\/p>\n

\"Holuhraun<\/a>

Holuhraun lava flow field map, 24 December 2014 by Institute of Earth Sciences, University of Iceland modified to show the evolution of the flow field. Click to enlarge. Source: http:\/\/en.vedur.is\/earthquakes-and-volcanism\/articles\/nr\/2947#des25<\/a><\/p><\/div>\n

Holuhraun Fieldwork Videos<\/h2>\n

The main purpose of this post is to share some videos that I recorded when I joined University of Iceland scientists studying the eruption in September. You can read about the trip and see photos in my Fieldwork at the Holuhraun<\/a> post.<\/p>\n

Fire fountains at the vent<\/h3>\n