New trigger for sudden volcanic eruptions identified

New trigger for sudden volcanic eruptions identified

A team of scientists have suggested that a rapid formation of bubbles in magma could trigger sudden volcano eruptions with no prior warning. The explanation holds the potential to change the approach to monitoring active and dormant volcanoes across the globe.

The experts have considered, for a long time, that volcano eruptions are caused by a build-up pressure of the slow accumulation of bubbly, gas-saturated magma, beneath volcanoes over a period of tens to hundreds of years.

However, new research indicates some eruptions may be triggered only days or months prior to the eruption event, by the rapid formation of gas bubbles in magma chambers very late in their lifetime.

A team of researchers from the University of Oxford and Durham, UK, in collaboration with the Vesuvius Volcano Observatory in Italy, have studied the Campi Flegrei volcano near Naples, to demonstrate the phenomenon.

"We have shown for the first time that processes that occur very late in magma chamber development can trigger explosive eruptions, perhaps in only a few days to months. This has significant implications for the way we monitor active and dormant volcanoes, suggesting that the signals we previously thought indicative of pre-eruptive activity, such as seismic activity or ground deformation, may, in fact, show the extension of a dormant period between eruptions," said Mike Stock, the lead author of the study, from the Department of Earth Sciences at the University of Oxford.

Research results imply that a change in the composition of gases emitted from the volcano at the Earth's surface could be a better sign of the coming eruption than seismic activity and ground deformation. This change could potentially provide an early warning sign.

The Campi Flegrei volcano last erupted in 1538 but has shown unrest signs recently. The scientists have studied the apatite mineral crystals thrown out during an ancient volcano eruption.

The apatite minerals act as 'time capsules', and by observing its compositions at different times during the magma body evolution, the researchers have showed that the magma that eventually erupted spent most of its lifetime in a bubble-free state, becoming gas-saturated only during a short time prior to the eruption.

Under these conditions of slow magma chamber growth, earthquakes and ground deformation at the surface may not signal the coming eruption, but simply track the arrival of new magma batches at depth.

"Now that we have demonstrated that this approach can work on a particular volcano, and given apatite is a mineral found in many volcanic systems, it is likely to stimulate interest in other volcanoes to see whether there is a similar pattern," said Professor David Pyle from the Department of Earth Sciences at the University of Oxford, a co-author of the study.

"This research will also help us refine our ideas of what we want to measure in our volcanoes and how we interpret the long-term monitoring signals traditionally used by observers."

See also:

Video credit: AdalianJM via YouTube


  • "Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions" - Michael J. Stock, Madeleine C. S. Humphreys, Victoria C. Smith, Roberto Isaia & David M. Pyle - Nature Geoscience (2016) - doi:10.1038/ngeo2639

Featured image: Campi Flegrei volcano. Image credit: Monica Munoz


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