Reviving the Past: New Insights on Bolivia's Uturuncu Volcano Activity

In a groundbreaking study published in the *Proceedings of the National Academy of Sciences* on July 15, 2025, scientists have revealed that the Uturuncu volcano in Bolivia, long considered extinct, shows signs of internal activity that challenge established geological definitions. This research, led by Professor Mike Kendall from the University of Oxford, uncovers over 1,700 small earthquakes that indicate the volcano's internal dynamics, suggesting it may not be as dormant as previously thought.

Historically, volcanoes are deemed extinct when no eruptions are recorded for at least 10,000 years. The Uturuncu volcano, which last erupted approximately 250,000 years ago, meets this criteria. However, local Aymara communities have reported sightings of sulfurous steam, hinting at the volcano's restless state. The study employed seismic tomography to map the volcanic system, revealing a network of conduits filled with magma and fluids beneath the Andes, specifically within the Altiplano-Puna Volcanic Complex, the largest known melt body in the Earth's upper crust.

According to Kendall, the research not only provides insights into Uturuncu but also establishes a framework applicable to other volcanoes that exhibit similar signs of life. "Our results show how linked geophysical and geological methods can be used to better understand volcanoes," he stated, highlighting the collaborative nature of the research team’s findings.

Further analysis by Professor Haijiang Zhang of the University of Science and Technology of China emphasized the importance of integrating petrophysics, chemistry, and fieldwork to interpret the geological activity. The study's findings suggest that any minor pressure fluctuations within the hydrothermal system might lead to observable ground deformations, a phenomenon reminiscent of a volcano preparing for an eruption.

Matthew Pritchard, a co-author of the study, noted the implications of their findings for other potentially active volcanoes. The United States Geological Survey identifies approximately 1,350 potentially active volcanoes globally, of which only around 500 have erupted in recorded history. "The new toolkit could be deployed on the more than 1,400 potentially active volcanoes and to the dozens of volcanoes like Uturuncu that aren’t considered active but that show signs of life," he remarked.

The research raises pertinent questions regarding volcano monitoring and public safety. The term 'extinct' can create a false sense of security among communities near such geological formations. The tragic eruption of White Island in 2019, which surprised tourists despite ongoing monitoring, exemplifies the need for more nuanced communication regarding volcanic activity.

As climate change continues to influence geological processes, the study indicates that changing rainfall patterns and retreating glaciers could affect volcanic systems worldwide. This potential for renewed activity underscores the necessity of continual monitoring and advanced research methodologies, such as tomographic scans, which are less invasive than drilling and can be repeated over time to track subsurface changes.

In Bolivia, new broadband seismometers have been installed around the Uturuncu volcano, and regional airports are incorporating deformation updates into their flight routing protocols. Researchers aim to expand their sensor networks across the southern Altiplano to better understand the interplay between rainfall and volcanic activity.

As the scientific community reevaluates the status of volcanoes long thought to be extinct, the case of Uturuncu serves as a poignant reminder that geological processes are complex and can defy simplistic categorization. The volcano's subtle movements may not herald an imminent eruption, but they do illustrate that the Earth's geological systems remain dynamic and worthy of ongoing research.