Deep within the Central Andes, the Uturuncu volcano in Bolivia, often referred to as the "zombie" volcano due to its last eruption occurring some 250,000 years ago, presents a subject of intrigue for geologists. Despite its dormant state, Uturuncu exhibits signs of unrest such as earthquakes and gas emissions. These phenomena are marked by a “sombrero” pattern of deformation—an uplift in the center coupled with subsidence in the surrounding areas.
Scientists recently attempted to unravel the mystery behind Uturuncu's unrest. An international team of researchers, including those from the University of Oxford, the University of Science and Technology of China, and Cornell University, have collaborated on a study using data from over 1,700 earthquake events. Through high-resolution imaging of the volcanic system's subsurface, they aimed to visualize the movement of magma and gases driving this unrest.
Professor Mike Kendall from the University of Oxford remarked, “I am very pleased to be involved in this truly international collaboration. Our results show how linked geophysical and geological methods can be used to better understand volcanoes, and the hazards and potential resources they present.”
Uturuncu is situated above the Altiplano-Puna Volcanic Complex, the Earth’s largest known magma body, with an active hydrothermal system connecting it to the surface. The research leverages seismic tomography, akin to medical imaging techniques, to explore the volcano's interior. This approach allowed the detection of varying seismic wave speeds through different materials, offering a three-dimensional view of the volcano’s complex internal structure.
The findings suggest that the "zombie"-like activity is mainly driven by the movement of fluids and gases beneath the volcano, which accumulate in reservoirs close to the crater, thereby explaining the central uplift. However, the likelihood of a near-term eruption is considered low.
The study holds significance for the local populace, underlining the necessity to evaluate the potential for future eruptions that could pose risks. The research team advocates for the use of combined seismological and petrological analyses to investigate other volcanic systems.
Researchers concluded that the study, published in the journal PNAS, could set a precedent for examining the anatomy of volcanic systems worldwide.