Overview
- Peer-reviewed research in Science reports that shear alone can nucleate gas bubbles in magma without a pressure drop.
- Experiments with CO2-saturated viscous fluids show bubbles form first along conduit walls where velocity gradients are steep.
- Existing bubbles promote nearby nucleation and merge into pathways that create early degassing channels.
- Volatile-rich magmas require less shear to generate and grow bubbles, making shear-induced nucleation more likely.
- Findings help explain quiet outflows at gas-rich systems such as Mount St. Helens and Quizapu and call for updating hazard models to include shear effects.