When the Bárðarbunga volcano, which is buried beneath Iceland’s Vatnajökull H2O ice cap, reawakened inward August 2014, scientists had a rare chance to monitor how the magma flowed through cracks inward the stone away from the volcano. The molten stone forms vertical sheet-like features known equally dykes, which forcefulness the surrounding stone apart.
Study co-author Professor Andy Hooper from the Centre for Observation too Modelling of Earthquakes, volcanoes too Tectonics (COMET) at the University of Leeds explained: “New crust forms where ii tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is hard to observe.
“However, inward Republic of Iceland this happens beneath dry out land. The events leading to the eruption inward August 2014 are the first time that such a rifting episode has occurred at that topographic point too been observed amongst modern tools, similar GPS too satellite radar.”
Although it has a long history of eruptions, Bárðarbunga has been increasingly restless since 2005. There was a especially dynamic menses inward August too September this year, when to a greater extent than than 22,000 earthquakes were recorded inward or around the volcano inward merely 4 weeks, due to stress existence released equally magma forced its agency through the rock.
Using GPS too satellite measurements, the squad were able to rails the path of the magma for over 45km earlier it reached a shout out for where it began to erupt, too continues to practise too then to this day. The charge per unit of measurement of dyke propagation was variable too slowed equally the magma reached natural barriers, which were overcome yesteryear the build-up of pressure, creating a novel segment.
The dyke grows inward segments, breaking through from i to the adjacent yesteryear the construct upwards of pressure. This explains how focused upwelling of magma nether key volcanoes is effectively redistributed over large distances to practise novel upper crust at divergent plate boundaries, the authors conclude.
As good equally the dyke, the squad establish ‘ice cauldrons’ – shallow depressions inward the H2O ice amongst circular crevasses, where the base of operations of the glacier had been melted yesteryear magma. In addition, radar measurements showed that the H2O ice within Bárðarbunga’s crater had sunk yesteryear 16m, equally the volcano flooring collapsed.
COMET PhD pupil Karsten Spaans from the University of Leeds, a co-author of the study, added: “Using radar measurements from space, nosotros tin flame cast an picture of caldera crusade occurring inward i day. Usually nosotros await to run into merely dissonance inward the image, but nosotros were amazed to run into upwards to 55cm of subsidence.”
Like other liquids, magma flows along the path of to the lowest degree resistance, which explains why the dyke at Bárðarbunga changed administration equally it progressed. Magma stream was influenced by too large yesteryear the prevarication of the province to start with, but equally it moved away from the steeper slopes, the influence of plate movements became to a greater extent than important.
Summarising the findings, Professor Hooper said: “Our observations of this trial showed that the magma injected into the crust took an incredibly roundabout path too proceeded inward fits too starts.
“Initially nosotros were surprised at this complexity, but it turns out nosotros tin flame explicate all the twists too turns amongst a relatively uncomplicated model, which considers merely the pressure level of stone too H2O ice above, too the trace exerted yesteryear the plates moving apart.”