Earth grew new layer under Iceland volcano
Saturday 27 May, 2017
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Earth grew new layer under Iceland volcano

Published On: Sat, Dec 20th, 2014 | Geology | By BioNews

By monitoring how magma flows through cracks in the rock away from a volcano, scientists have shed light on how the earthscrust forms.

When the Baroarbunga volcano in Iceland erupted in August, scientists found that the molten rock forms vertical sheet-like features known as dykes, which force the surrounding rock apart.

“New crust forms where two tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is difficult to observe. However, in Iceland this happens beneath dry land,” explained Andy Hooper from University of Leeds and co-author.

“Using radar measurements from space, we can form an image of caldera movement occurring in one day. Usually we expect to see just noise in the image, but we were amazed to see up to 55cm of subsidence,” said Karsten Spaans from University of Leeds and co-author.

The rate of dyke propagation was variable and slowed as the magma reached natural barriers.

The dyke grows in segments, breaking through from one to the next by the build up of pressure.

Thus magma under central volcanoes is effectively redistributed over large distances to create new upper crust at divergent plate boundaries.

Like other liquids, magma flows along the path of least resistance, which explains why the dyke at Baroarbunga volcano in Iceland changed direction as it progressed.

“Our observations of this event showed that the magma injected into the crust took an incredibly roundabout path and proceeded in fits and starts,” Hooper concluded.

The study appeared in the journal Nature.

Reference:

Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic system, Iceland. Freysteinn Sigmundsson, Andrew Hooper,Sigrún Hreinsdóttir,Kristín S. Vogfjörd, Benedikt G. Ófeigsson,Elías Rafn Heimisson,Stéphanie Dumont, Michelle Parks, Karsten Spaans, Gunnar B. Gudmundsson,Vincent Drouin,Thóra Árnadóttir, Kristín Jónsdóttir, Magnús T. Gudmundsson,Thórdís Högnadóttir,Hildur María Fridriksdóttir,Martin Hensch, Páll Einarsson,Eyjólfur Magnússon,Sergey Samsonov,Bryndís Brandsdóttir,Robert S. White,Thorbjörg Ágústsdóttir,Tim Greenfield,Robert G. Green,Ásta Rut Hjartardóttir, Rikke Pedersen,Richard A. Bennett,Halldór Geirsson,Peter C. La Femina,Helgi Björnsson,Finnur Pálsson, Erik Sturkell, Christopher J. Bean,Martin Möllhoff,Aoife K. Braiden & Eva P. S. Eibl. Nature (2014) doi:10.1038/nature14111

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