The internal lives of volcanoes are still an unrelenting enigma for scientists. Their interior structures, the ways that magma systems operate, the factors leading to eruptions—all are fertile grounds for research.
And there are few peaks of more interest than Newberry Volcano, located 20 miles outside Bend, which some believe could possibly erupt. It has also been considered a site for controversial geothermal power extraction since the 1980s.
Emilie Hooft, an assistant professor of geological sciences, is determined to see beyond Newberry’s rocky veneer and to understand just where magma lies within the volcano.
It was long thought that magma was stored in large brimming reservoirs far beneath the surface, but recent research suggests magma is far more diffuse, often located in small subterranean fissures and pockets, Hooft said.
“Part of the project is to figure out where the magma is located and that will tell us if Bend needs to worry about another eruption,” she said. “Newberry last erupted 1,300 years ago, which, geologically speaking, is very recent.”
To do this, she’s trying to expand and hone an old technology, seismic tomography, which uses sound energy waves to see inside volcanoes almost like a CAT scan looks inside a human being. At Newberry, Hooft and her team used timed explosions at eighteen different points near the volcano and measured the speed of the resulting waves as they passed through the peak.
The more solid and strong the rock, the faster the waves travel, while loose rock, rubble or magma causes waves to travel more slowly.
The waves are actually too big to pick up small areas of loose rock—or slow blobs as Hooft refers to them. After hitting the slow blobs, the distorted waves reform and “heal” themselves as they travel further away, obscuring the data. But successful detection of these areas is vital to gaining a complete picture of the volcano’s internal workings.
To address these problems, Hooft is working to perfect a new method, examining the data from the fainter and muddier—but potentially more telling—secondary waves.
“Imagine ripples in a pond reaching the edge and then bouncing back across,” she said. “That’s what secondary waves are like.”
These waves are sensitive enough to pick up smaller geological anomalies within the volcano. However, because they’re traveling across the volcano while the “pond” is still full of ripples, it can be harder to trace their trajectory, Hooft said. To extricate these secondary waves requires that mountains of data be collected and analyzed.
Hooft believes all this data crunching will pay off, and that secondary waves, once perfected, could provide a clear window to any volcano’s magma system.
“At some point, we could go to any volcano to figure out if there’s magma down there and if it’s a hazard,” she said. “We could figure out why different volcanoes behave so differently.”
Photo by George Slad