Researchers report in the journal Science that gas bubbles in magma can form not only from falling pressure but also from shear forces inside the conduit. When magma rises and pressure drops, dissolved gases form bubbles and can make eruptions violent. The new work explains why some gas-rich magmas still produce slow, calm flows.
Shear is the difference in flow speed between the conduit centre and the walls. The study shows that shear can create bubbles, and if these bubbles grow and join deep in the conduit they can form channels that let gas escape early. In laboratory tests the team used a viscous liquid like molten rock and saturated it with carbon dioxide. Above a shear threshold, bubbles formed suddenly. Higher initial gas supersaturation meant less shear was needed, and existing bubbles helped form more bubbles nearby.
The researchers combined experiments with computer simulations and found the effect is likely where viscous magma flows along conduit walls. One example is the 1980 Mount St. Helens eruption, which began with a slow lava flow while shear released gas; a later landslide opened the vent, pressure dropped rapidly, and the volcano exploded. Olivier Bachmann of ETH Zurich says models should include shear forces to improve hazard assessment.
Difficult words
- explosiveness — The ability to explode with force.
- influence — To have an effect on something.influenced
- shear — A type of force that causes layers to slide.
- viscous — Thick and sticky, not easily flowing.
- eruption — An explosion of a volcano.
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How might this research change how we monitor volcanoes?
- What are other factors that might affect volcanic eruptions?
- Can you think of other natural phenomena influenced by similar forces?
Related articles
Algorithms show how catalysts turn propane into propylene
Researchers at the University of Rochester developed algorithms that explain how nanoscale catalysts convert propane to propylene. The work reveals atomic features of metallic and oxide phases and could help improve industrial production methods.
Winter break activities that build children’s skills
A Virginia Tech educator says families can use everyday tasks during winter break to build thinking, planning and independence. Simple, hands-on activities like baking, budgeting and observing nature teach practical STEM and life skills without formal homework.
Dementia rising in Africa as researchers seek answers
Dementia is increasing in Africa as populations age. Research and evidence in the region are limited, so scientists study genetics, new detection tools and community measures while working with traditional healers to reduce stigma.
