A new model explains how a volcano erupts, revealing that gas bubbles form not just due to pressure drops but also from shear forces in the molten rock. Researchers at ETH Zurich simulated magma movement using a viscous polymer and found that bubbles primarily form near the conduit walls due to friction.
Unlike champagne bottles, where carbon dioxide forms bubbles when the cork is removed, the researchers discovered that shearing forces in magma create gas bubbles. This new explanation explains why some volcanoes erupt gently while others explode violently.
The model was tested with the 1980 Mount St. Helens eruption, which began with a slow lava intrusion and later exploded after a landslide opened the vent. The study’s findings suggest that shear forces can contribute to the formation of “degassing channels” in magma, reducing gas pressure.
To predict volcano hazards, researchers must update their models to include shearing forces in conduits. The new model provides a better understanding of volcanic eruptions and how they can be predicted with more accuracy.
Source: https://www.forbes.com/sites/davidbressan/2025/11/24/study-explains-why-some-volcanoes-explode-and-others-dont