Supervolcano Eruptions Explained By Scientists
The Nature Geoscience journal published a paper called “Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers” by scientists Wim Malfait and Carmen Sanchez-Valle of ETH Zurich (Switzerland), Paul Scherrer Institute in Villigen (Switzerland), Okayama University (Japan), the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon (France) and the European Synchrotron (ESRF) in Grenoble (France).
The researchers were able to reproduce the conditions inside the magma chamber of a supervolcano and were able to explain the factors that trigger explosion. They concluded: “Our research has shown that the pressure is actually large enough for Earth’s crust to break. The magma penetrating into the cracks will eventually reach Earth’s surface, even in the absence of water or carbon dioxide bubbles in the magma. As it rises to the surface, the magma will expand violently, which is the well known origin of a volcanic explosion.”
A supervolcano eruption already occurred 600,000 years ago in Wyoming in the United States, creating a huge crater called a caldera, in the centre of what today is Yellowstone National Park.
Read the abstract of the paper below:
Super-eruptions that dwarf all historical volcanic episodes in erupted volume and environmental impact are abundant in the geological record. Such eruptions of silica-rich magmas form large calderas. The mechanisms that trigger these super-eruptions are elusive because the processes occurring in conventional volcanic systems cannot simply be scaled up to the much larger magma chambers beneath supervolcanoes. Over-pressurization of the magma reservoir, caused by magma recharge, is a common trigger for smaller eruptions, but is insufficient to generate eruptions from large supervolcano magma chambers4. Magma buoyancy can potentially create sufficient overpressure, but the efficiency of this trigger mechanism has not been tested. Here we use synchrotron measurements of X-ray absorption to determine the density of silica-rich magmas at pressures and temperatures of up to 3.6?GPa and 1,950?K, respectively. We combine our results with existing measurements of silica-rich magma density at ambient pressures, to show that magma buoyancy can generate an overpressure on the roof of a large supervolcano magma chamber that exceeds the critical overpressure of 10–40?MPa required to induce dyke propagation4, even when the magma is undersaturated in volatiles. We conclude that magma buoyancy alone is a viable mechanism to trigger a super-eruption, although magma recharge and mush rejuvenation, volatile saturation or tectonic stress10 may have been important during specific eruptions.
Journal Reference:
Wim J. Malfait, Rita Seifert, Sylvain Petitgirard, Jean-Philippe Perrillat, Mohamed Mezouar, Tsutomu Ota, Eizo Nakamura, Philippe Lerch, Carmen Sanchez-Valle. Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers. Nature Geoscience, 2014; DOI: 10.1038/ngeo2042