Scientists from the University of Manchester have effectively modelled the process of bubble growth in volcanic magma using a new high-pressure vessel that can simulate the eruption process in the laboratory.
Since most volcanic activity occurs underground and is not observable, scientists have been able to record the kinetics of vesiculation in basaltic magmas in real time for the first time. Published today in Achievements of Science, The study sheds new light on one of nature's most amazing phenomena.
Volcanic eruptions vary widely, from small lava flows to powerful explosions, sometimes changing from one to the other in an instant.
In the worst cases, volcanic eruptions release huge volumes of magma and volcanic gases into the air. This causes catastrophic local destruction and often leads to widespread global effects, such as airspace closures and changing weather patterns.
Scientists have emphasized that the style of the eruption depends on how the gas dissolved in the magma is released. Parallels can be drawn between the way a waiter opens a bottle of champagne in a restaurant and the way champagne explodes when shaken by Grand Prix winners. Although both bottles contain the same amount of gas, the champagne leaves the bottles at completely different speeds.
The styles of volcanic eruptions depend on how easily the magma separates from the gas as it rises, with stronger gas-melt bonds leading to more explosive reactions. This study allowed scientists to observe and quantify the growth and coalescence of bubbles in real time in the magma as it rises to the surface.
The pressure vessel used in the laboratory experiments was thick enough to contain the enormous amount of stored energy, and X-rays (from the Diamond Light Source's I12-JEEP synchrotron radiation beamline) were used to see through the magma sample and make observations.
Dr. Barbara BoneciResearch Fellow in the Department of Earth and Environmental Sciences at the University of Manchester and lead author of the study, commented: “The experimental results obtained in this study, using a combination of our new vessel and X-ray synchrotron radiography, offer an improved understanding of the coupling and partitioning between magma and volatiles during conduit ascent. This research provides insight into the processes leading to eruption style transitions and ultimately has fundamental implications for hazard assessment and risk mitigation in areas of active basaltic volcanism.”
The pressure in the chambers could be increased or decreased in a controlled manner, allowing scientists to see how the expanding bubble walls collapse during coalescence at different pressures and temperatures, from 10 km down in the magma plumbing system all the way down to the conduit beneath the volcano.
The research is the result of a major NERC-NFS grant awarded to the University of Manchester, as well as the Universities of Bristol, Durham, Cambridge and Arizona State University in the US. A UKRI FLF project grant was also awarded to Manchester, and the research was completed in collaboration with colleagues at the ESRF in Grenoble, France, who developed the new experimental windowed pressure vessel used in the study.
The growth rates obtained using this new technique confirm previous estimates that used numerical and theoretical modeling. This study contributes to a better understanding of magma behavior and will significantly improve knowledge of volcanic processes, as well as aid in future hazard assessment and risk mitigation in areas of active volcanic activity.