One of the world’s most closely monitored volcanic systems lies beneath Yellowstone National Park’s bubbling geysers and steaming mud pots. Now, a team of geoscientists has uncovered new evidence about how this mighty system behaves and what might keep it from erupting.
Researchers from Rice University, the University of New Mexico, the University of Utah, and the University of Texas at Dallas have discovered a magma cap just 3.8 kilometers beneath Yellowstone’s surface. This cap, rich in volatile gases, acts like a lid, trapping heat and pressure below.
Scientists used a powerful truck to create small artificial earthquakes in a volcanic area. These quakes sent seismic waves into the ground, which bounced back from different underground layers. When the waves returned, they revealed a sudden change about 3.8 km below the surface. This unexpected finding suggests there might be a mix of molten rock and gas trapped beneath the ground.
Researchers analyzed various mixtures of rock, melt, and gas to determine the cause of the seismic signal. Their best match is a blend of molten rock and supercritical water bubbles trapped in porous rock, creating a gas-rich layer with about 14% space, half filled with fluid bubbles.
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The good news? This mixture isn’t at eruption-triggering levels. Instead, the system seems to be naturally releasing gas through tiny cracks, explaining why Yellowstone has so many hydrothermal vents emitting volcanic gases.
Using seismic imaging and advanced computer modeling, scientists found that the Yellowstone magma reservoir actively releases gas while remaining stable, indicating no immediate danger of eruption.
The team used controlled-source seismic imaging, where vibrations travel through the ground like tiny earthquakes. These signals revealed a deep underground boundary, providing new clues about the volcano’s structure.
Why does it matter?
- This discovery confirms Yellowstone’s volcanic system is still dynamic, even though it has been sitting beneath the park for millions of years.
- The volatile-rich magma cap allows gas bubbles to escape, working like a pressure-release valve, reducing eruption risk.
- The study establishes a new benchmark for volcano monitoring, enabling scientists to detect early warning signs in the future.
Beyond Yellowstone, these findings could have bigger applications for studying subsurface imaging related to geothermal energy, carbon storage, and hazard assessment.
Journal Reference:
- Duan, C., Song, W., Schmandt, B., et al. A sharp volatile-rich cap to the Yellowstone magmatic system. Nature 640, 962–966 (2025). DOI: 10.1038/s41586-025-08775-9
