Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers


Super-eruptions that dwarf all historical volcanic episodes in erupted volume1 and environmental impact2 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 eruptions3, but is insufficient to generate eruptions from large supervolcano magma chambers4. Magma buoyancy can potentially create sufficient overpressure4, but the efficiency of this trigger mechanism has not been tested. Here we use synchrotron measurements of X-ray absorption5 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 pressures6,7 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 rejuvenation8, volatile saturation9 or tectonic stress10 may have been important during specific eruptions.

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Figure 1: X-ray absorbance through the sample assembly at 1.02 GPa and 1,735 K.
Figure 2: Equation of state of dry and hydrous rhyolitic liquids.
Figure 3: Supervolcano magma chamber overpressure.


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We thank the ESRF for provision of the beam-time for these experiments and the SLS for the access to the IR facilities for the water analysis. We thank C. Yao for her help during data collection at the synchrotron and P. Ardia for providing the HGG0 and HGG5 sample. This research was supported by the Swiss National Science Foundation through grant 200021_130123 to C.S-V.

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W.J.M. and C.S-V. designed the study and W.J.M., R.S., C.S-V., S.P., J-P.P. and M.M. conducted the synchrotron experiments. W.J.M. and P.L. carried out the FTIR measurements and T.O. and E.N. provided the SIMS data. W.J.M. prepared the starting materials, conducted the electron microprobe analysis and carried out the data treatment and overpressure modelling. W.J.M and C.S-V. wrote the manuscript and all other authors commented on the manuscript.

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Correspondence to Wim J. Malfait or Carmen Sanchez-Valle.

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The authors declare no competing financial interests.

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Malfait, W., Seifert, R., Petitgirard, S. et al. Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers. Nature Geosci 7, 122–125 (2014).

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