24/06/2025
An international research effort coordinated by the Institute of Science, Technology and Sustainability for Ceramics (CNR-ISSMC) of Italy's National Research Council reveals how the rapid formation of nanocrystals in magma drastically increases its viscosity, fueling highly explosive volcanic eruptions and offering a new key to understanding the dynamics of such eruptions. The study, published in Communications Earth & Environment, opens new perspectives not only for volcanology but also for the design of advanced materials like industrial glass-ceramics
Explosive volcanic eruptions, capable of propelling ash and gas for kilometers, represent a significant geological hazard. Magma viscosity plays a crucial role: a more viscous magma traps gases more easily, increasing internal pressure to the point of triggering an explosion. An international research team, led by Pedro Valdivia Muñoz of the Bayerisches Geoinstitut (Germany) and coordinated by Danilo Di Genova of the Institute of Science, Technology and Sustainability for Ceramics of the National Research Council of Rome (CNR-ISSMC), with important contributions from other colleagues at the Bayerisches Geoinstitut (Germany) and Roma Tre University, has discovered a nanoscale mechanism that can make magma up to 30 times more viscous, and therefore more explosive, almost instantaneously.
The study, published in the journal Communications Earth & Environment, used advanced imaging techniques to observe, for the first time in real time, the formation of "nanolites"—iron and titanium oxide crystals smaller than a thousandth of a hair's diameter—in an andesitic magma, a type of magma with a typically intermediate viscosity common in many explosive volcanoes. This investigative capability, in which the team pioneered the filming of nanocrystal formation in glassy systems, opens new perspectives not only for volcanology but also for the design of advanced materials like industrial glass-ceramics, where controlling nanocrystallization is fundamental.
"We saw that these nanolites form in a matter of seconds once the magma reaches certain conditions," says Pedro Valdivia Muñoz of the Bayerisches Geoinstitut, the study's first author and a PhD student supervised by Danilo Di Genova. "But the real surprise is the chain reaction they trigger. Instead of being simple dispersed solid particles, the nanolites chemically alter the surrounding magma. Silica-enriched zones are created around the crystals, which are simultaneously enveloped by aluminum-rich shells. This nanoscale chemical heterogeneity is what is truly responsible for the impressive increase in viscosity."
It is a more complex mechanism than previously thought. "It's not just about the progressive depletion of iron from the liquid magma or the physical obstruction created by the crystals," the researcher continues. "It is the chemical reorganization at the nanoscale that radically changes the magma's behavior, significantly increasing its viscosity and thus making it flow with much more difficulty."
These findings have direct implications for understanding andesitic eruptions, which are typical of volcanoes like Sakurajima in Japan, whose magmatic composition was used as a reference for some of the experiments. "The rapid formation of nanolites and the consequent increase in viscosity during the magma's ascent could be key factors leading to explosive fragmentation. Furthermore, these heterogeneous zones could influence how fractures propagate through the magma and even facilitate the formation of gas bubbles, further amplifying the explosive potential," concludes Di Genova.
The research, which combines in situ high-temperature experiments with sophisticated nanoscale analyses and viscosity modeling, opens new avenues for assessing volcanic hazards, suggesting that even the smallest chemical and structural variations in the heart of the magma can have macroscopic and devastating consequences.
Per informazioni:
Danilo Di Genova
Cnr-Ismmc
danilo.digenova@cnr.it
Responsabile Unità Ufficio stampa:
Emanuele Guerrini
emanuele.guerrini@cnr.it
ufficiostampa@cnr.it
06 4993 3383
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