Explosive subglacial rhyolitic eruptions in Iceland are fueled by high magmatic H2O and closed-system degassing
Jacqueline Owen et al., Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK. Posted online 30 Nov. 2012; http://dx.doi.org/10.1130/G33647.1.
New research has discovered that magmatic water alone can power the explosivity of Icelandic rhyolite eruptions. Previously, scientists were aware of explosive rhyolitic eruptions from Iceland, but firm evidence of what might be powering the explosions and how much magmatic water the magma could contain were both lacking. The study by Jacqui Owen, Hugh Tuffen (both Lancaster University) and Dave McGarvie (The Open University) investigated samples collected from numerous subglacial rhyolitic edifices in Torfajkull (Iceland) that showed contrasting eruptive behavior. This included material from one of Iceland's most powerful subglacial rhyolitic eruptions which occurred 70,000 years ago and distributed thick ash layers across Europe. This new research shows a strong correlation between the explosivity of the eruptions and both the initial water content and "openness" of degassing; suggesting that magmatic volatile content alone is sufficient to drive powerful Icelandic eruptions, even those that initiate beneath thick ice sheets. Furthermore, Icelandic magma may contain much more water than previously thought, with values twice as high as expected being measured. This research helps explain the power behind some of Iceland's most explosive ash producing eruptions and may assist scientists working on the potential impact of future explosive rhyolitic eruptions on air travel.
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Geological Society of America