Scientists Uncover Hidden Activity in Bolivia’s ‘Zombie’ Volcano

A seemingly inactive volcano in southwestern Bolivia is stirring beneath the surface, according to research published April 28, 2025, in the Proceedings of the National Academy of Sciences. Despite not having erupted for more than 250,000 years, Uturuncu volcano has been quietly inflating at a rate of up to 1 centimeter annually, driven by fluid migration and gas accumulation below its crater.

Dormant But Not Dead: Inside a Volcanic “Zombie”

Cornell researchers initially detected signs of activity in Uturuncu two decades ago using satellite radar interferometry, which revealed a distinctive bullseye pattern of deformation around the volcano. The discovery prompted further investigation into this peculiar geological phenomenon.

“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,” said Matthew Pritchard, professor of earth and atmospheric sciences in Cornell Engineering, who led the Cornell team. “There are still processes going on.”

The 25-year research project culminated in a comprehensive study that combined multiple scientific approaches to peer beneath the volcano’s surface. Researchers deployed 48 seismometer stations around Uturuncu between 2009 and 2012, recording more than 1,700 earthquakes. They supplemented this data with measurements of gravity fields, natural electrical currents, and detailed rock analysis.

Creating a “CAT Scan” of an Ancient Volcano

This multidisciplinary approach allowed scientists to create something akin to a three-dimensional medical scan of the volcano’s interior. Their findings revealed a complex magmatic-hydrothermal system with clear pathways of fluid migration toward the surface and a gas accumulation zone beneath the crater.

The research team included scientists from Cornell University, the University of Science and Technology of China (USTC), University of Oxford, and ETH Zurich, with Ying Liu of USTC as the paper’s lead author.

What makes this discovery particularly valuable are its implications beyond volcanic monitoring:

• A new methodology for assessing eruption risk at other dormant volcanoes around the world
• Insights into how mineral deposits form, potentially aiding resource exploration
• Better understanding of long-term volcanic processes that occur over thousands of years
• A model for monitoring other similar “zombie” volcanoes globally

Mineral Formation in Action

Beyond the pure geological interest, Pritchard notes that studying Uturuncu provides real-time insights into economically significant processes. The fluid movement through the volcano’s system may help explain how valuable mineral deposits form.

“The idea is that fluids are flowing through molten rock and they pick up some minerals on their way, and then they take them somewhere and deposit them,” Pritchard explained. “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.”

Not Alone: A Global Phenomenon

Uturuncu’s “zombie” status isn’t unique. Pritchard’s satellite monitoring has identified similar volcanoes worldwide that continue showing signs of activity despite centuries or millennia of dormancy. Bolivia alone has approximately a dozen dormant volcanoes that warrant ongoing monitoring.

“These are sort of unique beasts,” he said. “But they’re not completely uncommon.”

While Uturuncu itself might not pose an immediate eruption threat, the research has implications for monitoring its neighbors. As Pritchard noted, “Uturuncu might not erupt, but some of its neighbors might.”

The research was supported by various organizations including the National Science Foundation, National Environmental Research Council of the UK, National Key Research and Development Program of China, National Natural Science Foundation of China, and the Royal Society. Technical support came from the EarthScope Consortium through its Primary Instrument Center at New Mexico Tech.