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What a gas
Volcanologists are also interested in learning more about what comes out of the volcano to understand Erebus’ effects on the atmosphere and environment.
That’s more the specialty of volcanologist Clive Oppenheimer, from the University of Cambridge, who is in his fourth straight field season on Erebus. Using an infrared spectrometer and other instruments, Oppenheimer has identified the composition of the ever-present gas plume that billows out of the volcano’s cone.
Like the lava boiling within Erebus, the makeup of the gases emitted from the volcano is also fairly uncommon. Evaporated water and carbon dioxide comprise about 99 percent of the gas, approximately in even proportions, Kyle said. The Antarctic volcano also emits a number of other gases in minute amounts including sulfur dioxide and carbon monoxide.
“I don’t think anyone’s measured levels of carbon monoxide that we’ve seen here,” Kyle said. “[Erebus is] putting out a gas of very unusual composition.”
Last year’s spike in activity also revealed a unique signature in the gas bubbles that exploded at the lake’s surface, according to Oppenheimer, speaking from the team’s hut outpost on the flanks of Erebus.
It turns out the proportion of carbon dioxide is much higher at the point of the explosion. Oppenheimer said it’s likely that the source of these gas bubbles is far deeper in the volcano than the gas normally emitted from the lava lake.
“The geochemistry of the gases is telling us something about the depth and the plumbing system and where those gases are coming from,” Oppenheimer said.
A natural polluter
In addition, some of the elements in the volcano’s magma are very volatile and escape in a gas form. These include elements such as lead, arsenic and mercury. The scientists believe trace amounts of these elements could be drifting at least as far as the South Pole, which sits at a fairly high altitude
“We can see Erebus in the snow at South Pole,” Kyle said. “People have seen lead in ice cores.”
Oppenheimer said one challenge is to determine how big of a natural polluter Erebus is to the Antarctic environment. He said current research suggests the perpetual output of certain Erebus gases such as bromine into the troposphere, the layer of atmosphere closest to the earth, could affect ozone.
(The scientists say the volcano has no effect on the ozone layer higher up in the stratosphere, where annual depletion caused by anthropogenic chemicals makes a hole form over the Antarctic around August.)
“I think it’s likely that Erebus has some kind of regional impact on the atmosphere, possibly on the ozone, but it will be another year or two of modeling to discern that,” Oppenheimer said.
There are a number of questions the scientists want to answer about the effects of the gas plume, which issues non-stop from the volcano. Where does the gas plume go? How does it affect the snow and ice? How long does the gas stay in the atmosphere?
“Because it’s so clean down here, that stuff does get spread out, and Erebus does have an impact on the environment,” Kyle said. “We’re trying to assess that.”
Learning in the field
A typical field season lasts about four to six weeks, with the team a mix of scientists and students. This season is no different, with one undergraduate and three graduate students from New Mexico Tech along with a fifth student from the University of Cambridge.
This is Christine Kimball’s second year on Erebus. A New Mexico Tech graduate student working on her master’s degree, Kimball said her fieldwork on the volcano has definitely influenced her future plans.
“It has been a really amazing experience so far,” Kimball said from the on-site laboratory on the volcano shortly before Christmas. “Antarctica is really why I went to graduate school at Tech in the first place to work with Phil. I think I’d like to continue to work in Antarctica in the future, and it’s really made me want to go for that PhD in the future and stay in research.”
Kimball’s specific project involves studying the geochemistry of the so-called Erebus crystals, a mineral called anorthoclase, a type of feldspar that consists of aluminum silicate. The ones ejected out of Erebus from the lava lake are highly unusual because of their size. Kimball is studying and collecting the crystals to learn more about their growth.
“It’s not well understood,” said Kimball, who plans to finish her thesis this coming summer back in the United States.
“Erebus is a great training ground for students … and I’ve made a great effort to bring students down here,” said Kyle, who estimated at least 20 students have written their theses on Erebus over the years.
Outfitted for research
One of the team’s primary missions each season is to repair and upgrade equipment. Storms packing winds in excess of 150 kilometers per hour can cause significant disruptions to year-round observation. The group relies on wind generators to power equipment during the winter but just such a storm trashed five of the generators this past year.
In addition to the seismometers, other instruments include microphones around the crater rim that detect explosions and earthquakes as well as high-precision GPS units that measure any deformation of the volcano. The latter occurs if additional magma comes into the system, causing the volcano to swell, a possible indication of a change in activity and eruptions. So far, the volcanologists have only detected slight variations, less than 5 millimeters per year.
“The thing about Erebus is it’s amazingly stable,” Kyle said. “It’s out there doing its thing with relatively unchanged behavior since the ’70s.”
The volcano, which bears the name of the son of the Greek god of Chaos, may be relatively static since scientists began studying it in earnest 35 years ago, but today’s technology is helping them change their ideas about its role in the ecosystem.
“We used to have our hammer banging on the rocks. Now we have sophisticated instruments. We’ve got one of the better instrumented volcanoes in the world,” Kyle noted. “We’re doing front-line science, where in the past we were doing exploration.”
NSF-funded research in this story: Phil Kyle, New Mexico Institute of Mining and Technology.