An article co-written by Boise State geoscientist Jeffrey Johnson and titled “Thermal vesiculation during volcanic eruptions” recently was published in the prestigious journal Nature. Johnson calls the article “paradigm shifting” because it is the first to highlight the importance of frictional heating during explosive volcanic activity.
Normally, as magma ascends to the surface it releases gas (a process known as exsolving). These gases are under enormous pressures and can expand explosively as magma rises. This study shows that viscous (or sticky) magma can be subjected to intense frictional heating (due to shearing) and this liberates even more gas, which further fuels volcanic explosions.
“We have discovered that sticky magma, such as is characteristic at Volcano Santiaguito in Guatemala, heats up as it rises toward the vent,” said Johnson. “This enables gas to further exsolve and increase the ‘explosivity’ of Santiaguito’s roughly hourly eruptions.”
Johnson and his co-authors argue that the effects of frictional heat have been under-appreciated. Future models that simulate volcanic activities worldwide will need to incorporate these vital thermal effects.
Johnson currently is leading a group of 60 collaborators at the Santiaguito site, comprising volcanologists from the Smithsonian, University of Liverpool, Michigan Tech and other institutions to gather additional measurements to continue the research.
This work is part of the first in a series of conferences called Workshops on Volcanoes, which is being funded through Boise State University by the National Science Foundation.
Follow their studies in progress at Twitter using #wov2016.