A Cornell-led research collaboration identified distinct mechanisms driving two historic eruptions of Mount Etna in Italy, according to findings published June 2 in Geochemistry, Geophysics, Geosystems. The study reveals that carbon dioxide, alongside water, acts as a critical volatile driver capable of triggering explosive volcanic activity.
Challenging Traditional Volcanic Assumptions
Volcanic explosivity depends on several variables, including magma viscosity and the behavior of volatiles—the gases trapped within the magma. For a significant period, the geological community operated under the assumption that water served as the primary volatile driver for eruptions. However, a research group led by Esteban Gazel, the Charles N. Mellowes Professor in the Department of Earth and Atmospheric Sciences in the Cornell Duffield College of Engineering, challenged this view.
In 2023, Gazel’s group demonstrated that carbon dioxide can trigger explosive eruptions. To explain the mechanics of this process, Gazel compared the behavior of volcanic gases to a common beverage.
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Imagine a bottle of soda. If you open that bottle without agitating it, you can drink it, but if you shake it up, all the bubbles get separated really fast, and you have an explosion,
Esteban Gazel, Charles N. Mellowes Professor in the Department of Earth and Atmospheric Sciences, Cornell Duffield College of Engineering
The study found that the plumbing systems of volcanoes are not consistent, even within a single volcano like Mount Etna. By analyzing two historic eruptions, the researchers identified that different mechanisms were at play, highlighting the complex nature of how volatiles separate and drive magma upward.
Utilizing Raman Spectroscopy for Magma Analysis
To uncover these mechanisms, the researchers utilized a new method involving Raman spectroscopy. This technique allows scientists to examine crystals formed within magma to measure micron-sized bubbles. These bubbles are extremely small, measuring roughly 1-10% the thickness of human hair
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The data extracted from these bubbles provides a mathematical pathway to understanding the volcano’s internal state. By determining the density of the carbon dioxide trapped in the crystals, researchers can apply a state equation to calculate the pressure. This pressure value then allows them to determine the depth at which the crystals formed.
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That technique gives us the density of CO2, and using a state equation we can transform that density into pressure, and pressure can be transformed into depth,
Maxim Gavrilenko, former postdoctoral researcher and first author of the study
Enhancing Volcanic Hazard Forecasting
The ability to differentiate between water-driven and carbon dioxide-driven eruptions provides geologists with a more nuanced toolkit for monitoring volcanic activity. Because the plumbing systems of volcanoes are vast and complex
, understanding the specific volatiles driving an event is essential for predicting the nature of the eruption.
By combining these new insights into volatile dynamics with the Raman spectroscopy technique, geologists can better assess the risk of future eruptions. The research emphasizes that identifying whether carbon dioxide or water is the primary driver can help determine if an eruption is likely to be explosive or more passive, which is critical for safety and risk management in regions surrounding active volcanoes.
