Major volcanic eruptions might be driven by gas dissolving back into magma
By Krystal Kasal, Phys.org
The identification of the mechanisms that trigger large volcanic eruptions is critical for hazard assessment; however, the exact processes remain inadequately understood. Traditionally, the prevailing theory attributes eruptions to volatile exsolution—where gas escapes from magma. This is especially noted in silica-rich volcanoes. Contrarily, a recent study published in Nature Communications suggests that the dissolution of gas back into the magma may actually precipitate the pressurization necessary for substantial eruptions.
Volatile exsolution vs. volatile resorption
Prior research has predominantly highlighted volatile exsolution as a significant factor leading to eruptions through increasing pressure within magma chambers. During volatile exsolution, gases, including water vapor, carbon dioxide, and sulfur, separate from the silicate melt, forming bubbles as the magma ascends or cools. This process diminishes solubility and results in considerable magmatic overpressure, thereby driving volcanic eruptions. Some studies indicate that within extensive volcanic systems, exsolved gases can buffer pressure, resulting in less frequent but larger eruptions.
The new study introduces the concept of volatile resorption, which involves gases dissolving back into magma. This phenomenon decreases the compressibility of magma, thus modulating the system's response to recharge and its overall stability, ultimately facilitating quicker eruptions due to the increased difficulty of compressing the magma. Researchers propose that volatile resorption can swiftly augment pressure in large silicic magma chambers, potentially triggering eruptions more rapidly than volatile exsolution.
Simulating the Aso caldera in Japan
To illustrate this theory, the researchers examined a historical volcanic eruption in Japan, focusing on the event known as "Aso-4," which took place approximately 86,000 years ago. The team employed a thermo-mechanical numerical model of magma chambers, calibrated with geochemical data obtained from the Aso volcano. The volcano emits a calcium phosphate mineral, apatite, which serves as a record of water saturation behavior in the magma. Data collected from Aso's apatite crystals contributed significantly to modeling the eruption process.
The simulations assessed various recharge rates, volatile contents, and thermal conditions to analyze when volatile resorption occurs and its impacts on chamber stability. Findings revealed that volatile resorption leads to a reduction in magma compressibility, which in turn amplifies pressurization and destabilizes the chamber. The simulations demonstrated that this mechanism results in eruptions occurring more swiftly compared to scenarios involving exsolution.
While these models simplify the complex mechanics of volcanic activity, the study lays a foundational groundwork for future investigations. The development of more intricate models and real-time monitoring could enhance the comprehension of volatile resorption, providing a novel approach to forecasting catastrophic volcanic eruptions, thereby safeguarding lives and mitigating economic repercussions.
Citation:
Major volcanic eruptions might be driven by gas dissolving back into magma (2026, March 27) retrieved from https://phys.org/news/2026-03-major-volcanic-eruptions-driven-gas.html
Source: Science X Network
DOI: 10.1038/s41467-026-70206-8
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