• The activity of the Uturuncu volcano in Bolivia, dormant for 250,000 years, is driven by the movement of heated geothermal fluids and gases rather than magma, reducing the likelihood of an immediate eruption.
• Scientists used seismic tomography and other geophysical methods to map the volcano's internal structure and understand the hydrothermal system, revealing the largest known active magma body in the Earth's crust.
• The research has implications for monitoring other potentially active volcanoes worldwide, helping to distinguish between those posing an imminent threat and those simply 'letting off steam'.

The Uturuncu volcano in Bolivia, dormant for approximately 250,000 years, has displayed signs of activity such as earthquakes and gas plumes. A recent study combined seismology, physics models, and rock composition analysis to determine that this activity is caused by the movement of liquid and gas beneath the surface, heated by a large magma body, rather than by an imminent eruption. This finding helps scientists understand the internal processes of 'zombie' volcanoes and could improve volcanic monitoring worldwide.

• What: Scientists discovered that the activity in the Uturuncu volcano is due to the movement of heated fluids and gases within a hydrothermal network, rather than an impending eruption.
• Who: Researchers from the University of Science and Technology of China (USTC), Oxford University, Cornell University, and other institutions.
• When: The study was published in April 2025 in the journal Proceedings of the National Academy of Sciences (PNAS), based on data collected from 2009-2012.
• Where: The Uturuncu volcano is located in the Andes mountains in Bolivia, South America.

The study's findings significantly advance our understanding of volcanic behavior, particularly in long-dormant volcanoes. By using a combination of seismic tomography, geophysical methods, and geological analysis, researchers were able to map the internal structure of Uturuncu and determine that its activity is driven by a hydrothermal system linked to a vast magma body. This discovery challenges previous assumptions about volcanic unrest and could lead to more effective monitoring strategies for identifying potential eruption risks. The economic implications, such as identifying mineral deposits, add another layer of significance to this research.

When people look at volcanoes, they’re like, ‘Oh, if it’s not going to erupt, we’re not interested in it.’ But actually volcanoes that look dead on the surface are not dead underneath. There are still processes going on.

It looks like it’s just the volcano degassing, letting off steam and calming down, if anything.

Our results show how linked geophysical and geological methods can be used to better understand volcanoes, and the hazards and potential resources they present.

Fluids are flowing through molten rock and they pick up some minerals on their way, and then they take them somewhere and deposit them. Even though we’re not really worried about this particular volcano erupting in the next few years, we can sort of see in real time the processes of this happening. Clearly there is activity underground that may be even, at some point, economically useful.

The investigation into Uturuncu's activity has revealed valuable insights into the processes occurring within long-dormant volcanoes. The discovery that a hydrothermal system is responsible for the volcano's unrest, rather than an imminent eruption, provides a more nuanced understanding of volcanic behavior. This research has the potential to improve volcanic monitoring efforts worldwide and may even lead to the identification of valuable geothermal energy sources and mineral deposits. Further research is needed to fully understand the long-term implications of these findings and to refine our ability to predict volcanic activity.