On the Edge of Explosions
Phil Torgersen
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The rumblings indicating that Amanda Clarke’s life was about to change would barely register on a seismometer. It was the summer of 1992 at Boeing headquarters in Seattle. Employees assembled to hear a pilot trainer lecture on a rare and cataclysmic aviation hazard: flying through volcanic eruption plumes. He recounted numerous harrowing incidents, including a KLM flight that plummeted 3 kilometers when ash clouds from Alaska’s Redoubt volcano extinguished all four engines.
In the audience that day sat Clarke, an aerospace engineering student intern whose interest in volcanoes had recently been sparked by hiking around Mount St. Helens. The lecture marked an unexpected end to her aeronautics career and an unlikely entree into the field of volcanology.
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“It started me thinking about the interface between aerospace engineering and something more natural or scientific,” says Clarke, who had become vaguely dissatisfied with a field in which the only jobs were “cog in a machine-types” for large corporations.
Though she didn’t change her major before graduating from Notre Dame in 1994, Clarke was on a trajectory to become a volcanologist. Following graduation, she was awarded a Fulbright scholarship to the Philippines to study how eruptions of Mayon Volcano affected local agricultural communities.
Over the next decade, she earned a Ph.D. in geosciences from Pennsylvania State University and conducted field research on active volcanoes around the world. She collected strata samples at Mount St. Helens, deployed volcanic measuring instruments in Cameroon and spent a near-fatal four months monitoring the volcano that devastated the island of Montserrat. As a Royal Society Research fellow at England’s University of Bristol in 2002, she began experimenting with small-scale eruption models. Currently she is happily ensconced as an assistant professor at ASU specializing in explosive volcanoes.
Attractive and professional, with shoulder-length blond hair, Clarke is the calm and collected polar opposite of the geologic events she studies. She is prone to understatement, referencing imminent massive volcanic explosions with phrases like “there’s some thought that there could be some significant event” and using such levelheaded terms as “micromanaging” to describe conducting mass evacuations from hazardous Red Zones. She’s the type of person you’d want with you when, say, sprinting away from a 1500-degree blast of hot ash, rock fragments, and noxious gases.
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“We weren’t exactly running. Well, we were a little bit running from the pyroclastic flow,” she says of the day she almost died while monitoring Soufrière Hills volcano on Montserrat.
“The volcano was breathing,” she recalls, referring to the pressurizing and depressurizing before an eruption. She and a colleague were taking GPS measurements of the volcano’s deformation — the bulging, subsiding or tilting that occurs when magma rises up the cone. When they radioed the chief scientist to ask permission to take more readings, he warned them that the seismometers were going haywire and to leave the area. Ten minutes later the pyroclastic flow avalanched down the slope, killing 19 local islanders.
“If the decision or timing had been slightly different, we would have been in an area that was quite unsafe,” she understates again. She says volcanologists are “fairly adventurous, but not overly so...We’ve had enough colleagues worldwide either be in accidents or be killed that people are cautious and aware of the dangers associated with being careless.”
so we don’t know much about them.
Clarke has found a far safer environment at ASU, using computer models and experiments to gauge the behavior of erupting material: the surge of magma from chamber to surface, the ooze velocity of lava and its interaction with topography. The ultimate goal is to save lives and improve volcanic hazard assessment. On Montserrat, for example, the volcano is again threatening to blast, this time Mount St. Helens-style. She and her colleagues are trying to replicate that to answer practical questions, she says: “Are people in danger? Who would be in danger? If they were inside a house would a person necessarily die? If they’re outside, normally clothed, would they die? Will trees get blown down?”
One of her primary tools of discovery is a fish tank-like apparatus into which she injects garnet-dyed fluid and small glass spheres to simulate an eruption. She then films the mushrooming clouds of material and analyzes their shape and speed with Sherlockian precision.
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Water may seem like an unlikely substance in which to replicate pyroclastic explosions in air, but Clarke says “it’s nearly impossible to duplicate the dynamic conditions with air.” It’s the density ratios that really matter, she notes.
Volcanology has come a long way since Pliny the Elder spotted something awry on Vesuvius, but it’s surprising how much is yet to be discovered about these geologic superstars. “Most of the world’s volcanoes that are potentially threatening to either populations around them or on a much bigger scale have not been studied in a geologic sense,” notes Clarke. “So we don’t know much about them.”
There are at least 1,500 active volcanoes on the planet and about as many professional volcanologists. But only a limited number of scientists are actually out there with boots on the basalt and tiltmeters in hand, so it’s vital to selectively study volcanoes from which they can extrapolate the most. “It’s difficult sometimes to make good decisions about field areas—which volcanoes to use as laboratories,” admits Clarke.
Despite the challenges, volcanologists are making strides each day in predicting the behavior of magma, ash and pyroclastic surges. More volcanoes are being monitored, she says, and instruments such as seismometers and remote sensing are capturing volcanic behavior with more precision than ever.
Many of these advancements have been employed at ASU and are still being developed here today. “ASU has a strong history in volcanology,” says Clarke, who says she is also pleased to be in Arizona because it’s “a very volcanologically active place, or has been in the past.”
In the future, Clarke hopes to increase the breadth and depth of the current experimental program and to develop field projects in Guatemala. She wants to expand her understanding of the global impact and importance of large eruptions, which are much more than just geologic events. They impact the structure of urban and rural civilizations, agriculture, sustainability and the populations of people that live in their wake. “Most volcanoes are in developing nations…and areas of rapidly increasing population density,” she notes. Eventually she’d like to become “an expert in the interaction between volcanic eruptions and the increase in urban populations.”
For Clarke, volcanoes are not only a unique vantage point from which to study the relationship between geology and people; they are the conduits that deliver information about the mysterious subterranean, making the invisible visible. “I like that they are somehow giving us a clue as to what’s going on in the subsurface,” she says. “[Volcanoes] bring the Earth’s depths to the surface. And we can learn something from that.”
Contact the reporter at keridwen77@yahoo.com.