Researchers found that a magma’s thermal history may be a key factor in determining whether an eruption becomes more vigorous or remains relatively gentle.
What happens deep beneath a volcano can determine whether an eruption unfolds as a slow-moving lava flow or explodes into towering fountains of molten rock. New research suggests that one overlooked factor may be the magma’s temperature history long before it reaches the surface.
A team of scientists led by the University of Manchester has found that unusually hot magma can remain crystal-free for far longer than expected, dramatically changing how it behaves during an eruption. The discovery, based on magma from the 2021 Tajogaite eruption on La Palma in Spain’s Canary Islands, could help explain why volcanoes fed by similar magmas often produce very different eruption styles.
Their findings, published in Nature Communications, point to a process known as “superheating.” In this state, magma is heated beyond the temperature at which crystals can remain stable. While geologists have long known that crystals influence the flow and explosiveness of magma, the new study shows that excess heat can effectively erase the microscopic building blocks needed for crystals to form in the first place.
The results provide new insight into a long-running scientific question about how a magma’s thermal history affects crystallization before and during eruptions.
Lead author Dr. Barbara Bonechi, a Research Associate at The University of Manchester, said: “The history of crystal and bubble growth can dramatically control how a magma erupts, in particular as more crystals grow, they eventually have a dramatic effect on magma viscosity. Until now, we did not fully understand the dynamics of crystal growth for magmas that received an injection of superheat just before ascent. But using our exciting and newly developed X-ray transparent pressure vessel combined with synchrotron X-ray microtomography we can actually observe these processes ‘in situ.’”
Recreating Volcanic Conditions in the Laboratory
To investigate the process, the researchers recreated volcanic conditions in the laboratory using magma from the Tajogaite eruption, which may have undergone superheating before and during its ascent.
The team used synchrotron X-ray microtomography at Diamond Light Source to observe crystallization in real time. They also conducted complementary ex situ experiments in Prague, which allowed them to monitor the process over longer periods under carefully controlled temperature and pressure conditions.
The experiments showed a dramatic difference in crystal formation. Magma that had not been superheated began crystallizing in about 20 minutes. Magma exposed to strong superheating, however, delayed crystal formation for more than eight hours.
Effects on Magma Ascent and Eruption Style
The researchers incorporated these experimentally measured delays in crystal nucleation into computer models that simulate how magma rises and changes as it moves through Earth’s crust.
The simulations revealed that long delays in crystallization allow magma to remain relatively fluid while ascending rapidly, potentially leading to intense lava fountaining. By comparison, magma that crystallizes sooner becomes more viscous and rises more slowly. This slower ascent gives gases additional time to escape, increasing the likelihood of gentler, effusive eruptions.
According to the researchers, these findings could improve the interpretation of volcanic monitoring data and help scientists better forecast eruption behavior.
Co-author Dr. Margherita Polacci, Senior Lecturer in Volcanology at The University of Manchester, said: “Current volcanic hazard models typically focus on magma chemistry, gas content, and pressure changes. This work suggests that pre-eruptive thermal history and crystallization kinetics may also play an important role in controlling magma ascent and eruptive behavior, with implications for volcanic hazard assessment.”
Reference: “Superheating in mafic magmas controls clinopyroxene nucleation delay and magma ascent dynamics” by Barbara Bonechi, Fabio Arzilli, Margherita Polacci, Alessandro Fabbrizio, Giuseppe La Spina, Eleni Michailidou, Elisa Biagioli, Richard A. Brooker, Jean-Louis Hazemann, Robert C. Atwood, Danilo Di Genova, Sumith Abeykoon, David A. Neave, Renat R. Almeev and Mike Burton, 8 June 2026, Nature Communications.
DOI: 10.1038/s41467-026-73352-1
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