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Can a volcano rise from death? The lofty peak of the Central Andes Mountains, Uturunk is known as the “zombie volcano.” It has not erupted for over 250,000 years, but still shows signs of activity similar to that seen in active volcanoes such as gas plumes and earthquakes.
Satellite radar images taken more than 20 years ago of Uturunk, the highest mountain in southwestern Bolivia, showed that forces within the volcano had pulled down an area near the top, about 93 miles (150 km) wide, creating a sombrero-like shape. Scientists recently looked closely at the Uturuncu to see if ongoing deformations and other activities were indications of the sleeping volcano being awakened.
By combining satellite data with analyses of seismic activity with computer models of how it responds to various pressures, the researchers have stitched together a clearer picture of Uturunk’s inner “anatomy” to reveal the cause of that anxiety. They reported their discoveries in the Proceedings magazine of the National Academy of Sciences on April 28th.
Volcanic eruptions usually occur when the magma below the volcano surges into underground pockets called magma chambers and escapes to the surface through vents and cracks. The eruption explodes when the magma becomes thick and traps gas, causing pressure to accumulate and release suddenly, forcing the magma to be expelled as lava.
However, research shows that it was not the case under Uturuncu. Rather, magma, gas, and Bliny fluids interacted in hydrothermal networks (systems with activities not fully understood) to produce volcanic zombie ramblings.
Below the Uturunk, about 6-12 miles (10-20 km) deep, is a vast reservoir of magma called the Altiplanopuna Magma Body. Spanning approximately 124 miles (200 km), it is the most famous active magma body for the planet’s crust. Previous studies suggested an active hydrothermal system connecting the magma reservoirs and the mountain ranges mentioned above, but it was unclear how magma and liquid interact within this network.
Using signals from over 1,700 seismic events between 2009 and 2012, scientists created high-resolution images of shallow crust under Uturunk. They also documented underground electrical and gravity shifts, recorded rock chemistry changes, and revealed unprecedented details of the channel system within the wateryama system below as they circulated geothermal heating fluid.
Researchers found that when magmatic bodies heat underground liquids and release gas, the gas and liquid move upwards and are collected in chambers below the volcanic crater. Their movement via Uturuncu caused earthquakes, released steam, deformed the volcanic rocks, causing surface rise of about 0.4 inches (1 cm) per year.
Dr. Mike Kendall, director of Earth Sciences at Oxford University, said Uturuncu’s internal dynamics not only explain its activity, but also suggests that the zombie will not be revived anytime soon.
“It’s not that seismic activity is increasing. The bad sign is the increase in seismic activity, then seismic activity that has started moving from depth to much shallower depths. This usually indicates that the magma is moving,” Kendall told CNN.
“We haven’t seen anything like that,” he said. “It looks like it’s a volcano degassing.
Using multiple techniques was an important part of focusing on Uturunk’s underground structures, according to geologist Dr. Benjamin Andrews, director of the Global Volcanic Activities Program at the Museum of Natural History in Washington, DC.
The way in which seismic activity, rock chemistry and physics can be investigated on its own “but will have interesting but somewhat vague results,” says Andrews, who was not involved in the study. Together, these methods refer to hydrothermal systems rather than spike magma as a cause of uturuncu activity, providing a snapshot of the interaction between subvolcano magma, rocks and liquids.
“This (study) is important for understanding the bodies of volcanoes, granites and ore bodies, and it is also important to recognize that some volcanoes can be very active.
For decades, the global volcanic activity programme recorded around 50 zombie volcanoes more than 12,000 years ago, but less than 2.6 million years. Dr. Matthew Pritchard, a professor of geophysics at Cornell University in New York, said the signs of their activity are “geothermal features like hot springs and fumaroles (openings where hot gas escape).)
As utruncu is one of dozens of zombie volcanoes tracked by scientists around the world, new findings will help identify which zombies are at risk of erupting. Some zombies have shown increased surface temperatures and are already being investigated as a potential source of geothermal energy, and “many people are ripe for further investigation” about mineral deposits, Pritchard told CNN via email.
“Some have been in long and slowly decline, and just cool off from the previous hot season. Eventually, there may be some increase in activity,” he said. “But we still don’t know how to distinguish them.”
A peer into the volcano’s internal pipelines could reveal possible targets for leveraging geothermal energy and accessing technology-critical metals, such as copper, nickel and platinum, Kendall added. This combination of methods also helps you analyze not only zombies but all types of volcanoes.
“This is a really good way to better understand volcanic anatomy during development,” he said. “This is extremely important for risk and hazard assessments.”
Mindy Weisberger is a science writer and media producer who appeared in Live Science, Scientific American and How It Works Magazine.