By Thomas Guengerich
SOCORRO, N.M., March 12, 2009 – New Mexico Tech earth scientists recently returned from a highly successful field season in Antarctica where they undertook a seismic experiment that will provide a three dimensional image of the inside of an active volcano. A team of 13 faculty, students and support staff spent three months studying the inner workings of Mt. Erebus, the southernmost active volcano in the world.
Right: Four members of the New Mexico Tech team in Antarctica pose for a photo in an ice cave. The crew dealt with harsh conditions, but the weather was much more cooperative this year than last year. Photo by John Wood, for New Mexico Tech.
“The fundamental objective was a seismic experiment to image the inside of a volcano,” expedition leader Dr. Phil Kyle said. “It was a very ambitious experiment in many ways especially in a difficult environment like Antarctica. An experiment of this magnitude has not been done successfully at any volcano.”
Erebus volcano is one of only a handful of volcanoes with a permanent lava lake. Surprisingly, Erebus volcano in frigid Antarctica is the most accessible.
“The lava lake is a window to the inside of the volcano,” Kyle said. “In simple terms, the magma chamber is the heart of the volcano. By observing the lake we can see what is going on with the magma chamber. So fundamentally, we can see inside the volcano.”
The team installed 80 small 3-component seismometers in a grid over the summit of the volcano. They then set off more than a dozen explosions, which sent seismic waves through the upper part of the volcano. The seismic waves travel through rock at a relatively constant velocity, but react differently when they hit the magma chamber or areas of rock heated by the magma. By collating data from multiple seismic sensors, the team will produce a detailed 3-D image of the magma chamber.
To understand the deep structure under the volcano a further 20 seismometers were placed in a 50 miles-long line across Erebus and Ross Island. Larger explosions using over a half ton of ANFO were set off along the line of seismometers. Kyle and the Tech team hope this aspect of the work will provide a less detailed but important image of the crust that underlies the volcano.
“The field work was blessed by near perfect weather for most of the three-month field season and by superb helicopters support from the U.S. Antarctic Program,” Kyle said.
During the previous three-month field season in 2007-08 the New Mexico Tech team was only able to install 23 of a planned deployment of 25 broadband seismometers on Erebus, due to long periods of bad weather.
“It was some of the worst weather I have experienced in my 37 years working on Erebus. What a difference a year can make,” Kyle said with a smile.
Left: Dr. Daria Zandameneghi, a post-doctoral fellow at New Mexico Tech, stands near a volcanic â€œbombâ€ that is only a few years old. Photo by John Wood, for New Mexico Tech.
Dr. Daria Zandameneghi, who is working as a post-doctoral fellow at New Mexico Tech, designed and supervised the deployment of the 80 seismometers over the summit of the 12,500 foot high volcano. Now that she is back from Antarctica she will assemble all the data using computer modeling, converting seismic waves into visual images.
“We’re hopeful that we’ll have a greater understanding of how Erebus volcano works,” Kyle said. “And this will help expand our understanding of all volcanoes.”
The team borrowed seismic instruments from IRIS-PASSCAL, the national lending library that is conveniently located at New Mexico Tech.
Pnina Miller, a staff scientist at IRIS-PASSCAL, was the team member who was principally responsible for assembling, servicing and shipping the sensors. She was assisted by Robert Greschke also a staff scientist from IRIS-PASSCAL.
Right: In early November 2008, Pnina Miller from IRIS -PASSCAL services a seismic station at 11,000 feet altitude near the summit of the active Erebus volcano in Antarctica. In the background is the volcanic gas plume emitted from a permanent lava lake in the summit crater of the volcano. Photo by Phil Kyle, New Mexico Tech.
“Deploying all these sensors was a major undertaking,” she said. “We have other projects in Antarctica, so I service all the seismometers. Some are buried in snow, so it’s logistically difficult.”
Graduate student Matt Zimmerman was enlisted to help deploy the sensors because he had experience in Antarctica with a previous Tech mission and got a taste of Erebus during the 2007-08 field season.
“I have a strong back and weak mind,” he said jokingly. “So I was perfect for this assignment.”
This year’s expedition was Miller’s third trip to Antarctica. In her position as staff scientist, she has visited research projects in Uganda, Tanzania, Costa Rica, Venezuela and Jordan. Upcoming trips include China, Tibet and Kyrgyztan.
Left: Matt Zimmerman (right) of New Mexico Tech drills a 30-meter hole, in which explosives are detonated to created a seismic wave that travels through the Erebus volcano. Photo by John Wood, for New Mexico Tech.
“I have the best job in the world,” she said. “Our instruments go all over the world – and so do I.”
For instruments that were deployed in Antarctica the year before, early in the 2008-09 season Miller and Kyle swapped out their memory cards and sent the data back to Socorro for interpreting.
“With this experiment, you never know what you’re going to get until it’s all over,” Zandameneghi said. “These seismometers are very good, so I’m confident they’ll work.”
“If this works,” Kyle said. “We might go back with 500 seismometers to look at the ‘bowel’, if you like, and what lies below the magma chamber.”
The other experiments included a variety of chemical and geological studies. Dr Clive Oppenheimer, a scientist from the University of Cambridge and a frequent visitor to New Mexico Tech, examined the gasses coming from the lava lake.
Dr. Cathy Snelson, assistant professor of geophysics, helped design this year’s seismic experiment after a brief stint on Erebus in the 2007-08 field season. A growing family kept her away from Erebus this year. This year’s expedition was joined by a high school biology teacher from California. Jon Wood, who had been to Antarctica in the 1980s, was selected to join the group as a guest researcher.
The National Science Foundation sponsors teachers to accompany about a half-dozen expeditions every year.
Wood was selected from more than 30 applicants to accompany and support the New Mexico Tech team. Wood has a bachelor’s in biology and had worked in Antarctica in the 1970s and 80s prior to becoming a teacher.
“I’ve had the urge to go back for quite a while,” he said. “My goal is to reach as many classrooms and students as possible – with attention on the environment. Volcanoes have a huge impact on climate and the atmosphere and I’d like to give kids a real sense of that from the scientific angle.”
Wood was an active participant in the seismic experiment. He helped prepare and deploy sensors. Kyle said Wood was an important member of the research team. He also maintained a daily on-line diary, fielded questions from students and posted dozens of photos from Antarctica.
Most of the questions came from his school district in Fountain Valley, Calif., but students from across the nation were welcome to pose questions. Wood answered many questions about the temperature: “How cold is it down there, Mr. Wood?” Students also asked him detailed questions about the environment, volcanoes, chemistry and geology.
– NMT –