Volcano warning: Why volcanoes violently erupt after decades of being dormant – study

Researchers now understand what is responsible for the violent eruptions of long-dormant volcanoes. University of Bristol volcanologists have revealed the role crystalline so-called “nanolites” – which are so tiny they are actually 10,000 times smaller than the width of a human hair – play in apocalyptic explosions.

These nanolites have now been identified as the secret ingredient behind the violent eruptions of otherwise placid and predictable volcanoes.

This discovery provides an eloquent explanation for violent eruptions

Dr Danilo Di Genova

Despite their small scale, they play a key role in the viscosity of erupting magma, resulting in hitherto unexplained volcanic eruptions.

Dr Danilo Di Genova of the University of Bristol and lead author of the groundbreaking study believes this work has profound implications for studying some of the planet’s best-known volcanoes.

He said: “This discovery provides an eloquent explanation for violent eruptions at volcanos that are generally well behaved but occasionally present us with a deadly surprise, such as the 122BC eruption of Mount Etna.

“Volcanoes with low silica magma compositions have very low viscosity, which usually allows the gas to gently escape.

“However, we’ve shown that nanolites can increase the viscosity for a limited time, which would trap gas in the sticky liquid, leading to a sudden switch in behaviour that was previously difficult to explain.”

Dr Richard Brooker, also from Bristol’s Earth Sciences department, revealed how they reached their surprising conclusion in a statement.

He said: “We demonstrated the surprising effect of nanolites on magma viscosity, and thereby volcanic eruptions, using cutting-edge nano-imaging and Raman spectroscopy to hunt for evidence of these almost invisible particles in ash erupted during very violent eruptions.”

“The next stage was to re-melt these rocks in the laboratory and recreate the correct cooling rate to produce nanolites in the molten magma.

“Using the scattering of extremely bright synchrotron source radiation (10 billion times brighter than the Sun) we were able to document nanolite growth.”

“We then produced a nanolite-bearing basaltic foam (pumice) under laboratory conditions, also demonstrating how these nanolites can be produced by undercooling as volatiles are exsolved from magma, lowering the liquidus.”

Professor Heidy Mader, also involved in the study, thinks the volcano research may be one of the most important in recent decades.

She said: “By conducting new experiments on analogue synthetic materials, at low shear rates relative to volcanic systems, we were able to demonstrate the possibility of extreme viscosities for nanolite-bearing magma, extending our understanding of the unusual (non-Newtonian) behaviour of nanofluids, which have remained enigmatic since the term was coined 25 years ago.”

The scientists suggest the next step is to model this dangerous, unpredictable volcanic behaviour in real-life volcanic environments.

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