UWM Volcanologist Explains Eruption Forecasting on PBS Program 'Nova'

Barry Cameron arrived on campus Nov. 3 for what seemed like an ordinary work day. Instead, the unsuspecting assistant professor found the entire geosciences department abuzz about a program on the PBS series NOVA that aired the night before.

In the program, "Volcano under the City," Cameron give commentary on the complexities of predicting volcano eruptions. But he wasn't aware that he had been included on the final cut of the show, and he didn't watch it because he doesn't own a television.

"I've been to volcanoes in East Africa, but not to Nyiragongo, and I told the producers that," he says. "I wasn't sure if they would use any of the interview."

Cameron, who has studied volcano activity in five countries, had met the producer of NOVA at a meeting of scientists back in the spring. He was later invited to come to Denver for an on-camera interview to describe the process volcanologists use to predict eruptions.

His commentary augmented a program about determining the next eruption of the Nyiragongo volcano in central Africa. The program follows a French scientist, Jacques Durieux, who set out to collect gas and magma samples from the volcano, which has been spewing white smoke from its crater since March.

"What makes Nyiragongo unique is that it has had the fastest lava flows ever recorded – up to 60 miles per hour," says Cameron. "Normally, lava flows are the least dangerous kind of eruption, in terms of human fatalities, because you can simply get out of the way. But with flows that fast, you can't outrun them."

In addition, a network of fissures, or cracks in the earth where magma can reach the surface extend in all directions from this volcano. The fissures mean that lava can reach people miles away from the mountain very quickly and many, in fact, lie on the site of the city of Goma.

The stakes have never been higher for volcanologists searching for the exact warning signals. About 2 million people live near Nyiragongo, making it the rule rather than the exception. With a burgeoning world population, an estimated half-billion people live close to the flanks of an active volcano.

Seismic monitoring is still the best method of tracking volcanic activity, he says, though scientists are also using extremely accurate satellite imaging to find out if a volcano is "deflating" or rising on its flanks. Unfortunately, monitoring is especially difficult to keep up in developing countries, says Cameron, who has been a consultant to the Guatemalan government on volcano findings.

A third way to obtain clues is by analyzing the chemistry of gases in the outlets and the magma, key information in determining if the eruption will be the more effusive lava flow or a violent, or pyroclastic, flow that blasts magma, gas and steam high into the air.

"So not only do we want to know when, we want to know what kind," says Cameron.

As magma rises from a chamber miles below the crater, gases dissolved in water form bubbles. How fast the magma comes to the surface and how its gases are released dictate what kind of eruption will occur.

It's like shaking up a soda bottle and then opening it, he says. If you do it fast, soda goes everywhere.

"The very sensitive ratio between sulfur dioxide and carbon dioxide often tells us how close the magma is getting to the surface," he says. "High amounts of carbon dioxide mean the magna is still very deep, which indicates to me that there isn't an imminent threat."

Scientists at Nyiragongo found higher levels of carbon dioxide in the fissures, but also evidence that the magma with bubbles was rising quickly in the crater, presenting mixed signals. A factor they didn't test, but one that Cameron researches, is the use of water content in the sample as an indicator of the state of the magma.

"What I would have liked to see them measure was the water content of the product coming from the crater," he says. "If it hasn't lost a lot of water during its rise to the surface, then it would mean that it still contained a lot of gas, and gas is the driving force of any explosive eruption."

Although Nyiragongo had not yet erupted as of mid-November, Cameron believes it's only a matter of time. "It's due to erupt soon because it's been a very active volcano and it has extruded huge amounts of lava before. There tends to be a cycle to them."

He also believes it will be an effusive eruption, similar to the last eruption in 2002. The volcano's next-most recent eruption, in 1977, was also the passive kind, he says, but the speed of the lava flows were record-breaking.

Of course, it's still an educated guess.

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NOVA Transcript: http://www.pbs.org/wgbh/nova/transcripts/3215_volcanoc.html

More on Cameron: http://www.uwm.edu/Dept/Geosciences/People/faculty.html

Research Profiles: http://www.uwm.edu/Dept/Grad_Sch/Publications/ResearchProfile/featured_4a.html

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