SOCORRO, N.M. July 20, 2009 – New Mexico Tech geophysics professor Dr. Jeffrey Johnson recently completed a successful month-long field course studying the Tungurahua Volcano in Ecuador.
|Students in New Mexico Tech's field course in Ecuador pose in front of Volcan Tungurahua during a June expedition. The town of Banos can be seen on the slopes of the volcano. From left are Sarah Meyer of UC-Santa Cruz, Sarah Hanson-Hedgecock of the University of Buffalo, Niranjan Khalsa of New Mexico Tech, Branden Christensen of the University of Alaska-Fairbanks and Carolyn Parcheta of the University of Hawaii-Manoa. Photo by Hunter Knox/New Mexico Tech|
Sixteen graduate students from 12 universities in four countries – including three from New Mexico Tech – spent June in Ecuador learning about volcanoes and their inner workings. Johnson led the graduate level class, Geophysics 572, along with New Mexico Tech scientists and instructors from the Instituto Geofísico of the Escuela Politécnica Nacional in Ecuador.
“This was one of the best classes I’ve ever taken,” doctoral student Hunter Knox said. “Ecuador is an excellent natural laboratory for teaching students about volcanoes.”
The New Mexico Tech instructors included Dr. Rick Aster, geophysics professor and chair of the Earth and Environmental Science Department, geochemist Dr. Nelia Dunbar, geochronologist Dr. Bill McIntosh and geophysicist Dr. Mark Murray.
Field equipment for the course was supported by the IRIS PASSCAL Instrument Center at New Mexico Tech. Supported by the National Science Foundation, the Instrument Center is the nation’s leading facility for academic seismic instrumentation and field support.
The course also gave the New Mexico Tech scientists an opportunity to build relationships and expand partnerships with colleagues in Ecuador.
“It’s an exciting time for science in Ecuador,” Aster said. “We have all sorts of ongoing associations there. They have a great group of people and they’re at the forefront in South America in building their national Earth science and hazard reduction capacity.”
Mario Ruiz, the principal seismologist at the Instituto Geofisica, earned his master’s in geophysics in 2004 from New Mexico Tech, where he studied with Aster.
“Because of our historic ties to the Ecuadorian science community through Jeff, me and others, we’re in a great position to work with them in science and education in the future,” Aster said. “We hope to bring more Ecuadorian students to New Mexico Tech and send our faculty and students down there.”
Dunbar and McIntosh have worked in several other South American countries, but never Ecuador. Dunbar said they developed some new partnerships and have begun projects based in Ecuador.
“I brought back samples to look at the chemistry of a sequence of very explosive eruptions at the volcanic center of Quilotoa,” she said. “The scientists in Ecuador seemed really happy that we were interested in collaborating with them and producing high-quality geochemical and geochronological analyses on rocks from Ecuadoran volcanoes.”
|Geophysics professor Dr. Jeffrey Johnson demonstrates to graduate students how to set up a seismometer station in Ecuador in June. New Mexico Tech Photo|
Dunbar has already started to analyze the volcanic glass and crystal samples in her electron microprobe laboratory at the Bureau of Geology at New Mexico Tech.
Each of the Tech scientists said Ecuador is vibrant and inspiring.
“It’s a spectacular place to work and the Ecuadorians have made a commitment to reducing natural hazards and learning more about the geophysics of their nation, including the installation of a new state-of-the-art national seismographic network,” Aster said.
Knox said the Ecuadorian people take seismic safety quite seriously, largely due to the proximity of metropolitan areas to active volcanoes.
“The level of hazard is tremendous,” Dunbar said. “There’s a big steaming volcano – Guagua Pichincha – looming over the capitol city, Quito, so there’s good reason to think about science.”
“When the volcanoes start to rumble and shake, people become concerned,” Knox said. “Volcano seismology is relevant. People have to worry about hazards.”
Ecuador has a population of 14.5 million and is about the size of Wyoming. The country has five active volcanoes and overlies a major subduction zone. Johnson selected Volcan Tungurahua as the study site because it has proved to be a reliable source of both seismicity and infrasound data. Since it started erupting in 1999, the volcano’s vent has typically stayed open, providing the ultimate outdoor teaching laboratory where students can deploy instruments for just a few days and collect significant data, he said.
Johnson is an international leader in the growing field of studying infrasound waves, the sub-audible, low frequency sound waves created by volcanoes, volcanic earthquakes and other phenomena.
“I’ve also been interested in recording earthquake motions both in the ground and in the air in order to be able to infer what’s happening at the vent when you can’t see the volcano,” he said. “I always deploy both seismometers and infrasonic microphones – a tool capable of quantifying the concussions in the atmosphere.”
|Dr. Mario Ruiz, Omar Marcillo and Dr. Jeffrey Johnson on the slopes of Volcan Tungurahua in Ecuador. Ruiz is a 2004 Tech graduate and the lead seismologist at the Instituto Geofisica in Ecuador. Marcillo is a Tech student who hails from Ecuador. New Mexico Tech photo|
Johnson’s course focused on the deployment and maintenance of acoustic-seismic arrays, data processing and physical volcanology. Johnson taught students about volcano seismology, video and infrasound instrument deployment. Students collected and retrieved data, then processed and analyzed the infrasound data. The course was equally divided between field work, lectures, physical volcanology field trips and hands-on data analysis.
The course is the second summer expedition Johnson has led. The 2008 field course was in Hawaii and was 11 days long. He plans to alternate summer field courses between Ecuador and Hawaii.
“Primarily, it was a teaching class,” Johnson said. “But we also recorded some very high quality data, thanks to the fact that the volcano was very cooperative. We entered the experiment when it was erupting nearly continuously.”
Volcan Tungurahua erupted five to 10 times each day and periodically produced large “cannon shots.”
“Those cannon shots produced excellent signals that we can use to study eruption physics,” he said. “We were there for a 12-day deployment and we hit it just right with a nice level of activity with a reliable source of volcanic earthquakes and infrasound.”
The team set up camp in the vacation town of Banos at the foot of Tungurahua, which towers to 16,500 feet. During the first week, Johnson and the students deployed a seven-station seismic array and a 10-component infrasonic network.
Johnson and Tech graduate student Omar Marcillo, a native of Ecuador, taught the students how to set up infrasound recording instruments and seismometers and how to analyze data.
“We were interested in understanding how earthquakes relate to eruptive phenomena,” Johnson said. “Through our instrument deployment, we had the capabilities to understand where these quakes were located within the volcano.”
During the first week, the class witnessed a rare occurrence – a rain-mobilized ash flow, or lahar, tumbling down one of Tungurahua’s drainages. Click here to download the video.
|Graduate students Carolyn Parcheta (left), of the University of Hawaii at Manoa, and Kristen Chojnicki of Arizona State, pose in the shadow of Volcan Tungurahua in Ecuador. New Mexico Tech photo|
“We serendipitiously stumbled upon some signals that were associated with lahars,” Johnson said. “Anyone can watch a volcano erupt, but to be able to watch a lahar is rare. That was especially exciting. Plus, lahar signals are of interest because they are a principal volcanic hazard.”
Niranjan Khalsa of New Mexico Tech was one of two undergraduate students on the trip. She was effusive with praise for the quality of the learning experience.
“It was amazing,” she said. “We got to do everything from start to finish. I had no experience with seismometers or volcanoes, so it was super cool and fun.”
The students helped scout locations to place two arrays of instruments. Each station was placed in a trash-can-style bucket and buried in the mountainside. The stations were roughly 100 meters apart and set in roughly a cross-shaped configuration. The first array of seven instruments included both infrasound microphones and seismometers. The second array was just infrasound. In addition, the team set up time lapse cameras trained at the volcano.
“This is a novel class,” Johnson said. “Lots of folks do field science, but they are usually geologically focused. This is fundamentally different in that we brought our hardware to understand and record ongoing earth movements using geophysics. Our students had the opportunity to get dirty in the field and gather their own data.”
During the second week, the group set out on a whirlwind volcano road trip while waiting for the Tungurahua instruments to collect data from volcanic earthquakes. Scientists from the Instituto Geofisica led tours of the nation’s volcanic areas, with supporting lectures by the New Mexico Tech professors. After the weeklong tour, the group returned to Banos for instrument redeployment and a week of data synthesis and interpretation.
Knox is studying volcano seismology and had plenty of experience with the instrumentation prior to the trip. She has worked abroad as a professional engineer and participated in a New Mexico Tech research expedition to the Mount Erebus Volcano in Antarctica. The Ecuador trip was unique, she said.
“You can read a lot of papers and text books, but when you are standing on a volcano, looking at the deposits, hearing it and feeling it erupt and explode, it gives you an intuitive feeling about the processes going on,” she said. “Tungurahua is a dynamic volcano with cannon shots, earthquakes and lahars. We began to develop an understanding of a broad spectrum of volcanic activity.”
Johnson said each small eruption was especially satisfying to experience, knowing that the corresponding elastic wave radiation was being recorded.
|New Mexico Tech professor Dr. Jeffrey Johnson (right) observes as three graduate students check the GPS device they are attaching to a seismic station near Volcan Tungurahua in Ecuador. From left are Aida Reyes of National Autonomous University of Mexico, Ashley Edelman of UNM and Aaron Gutierrez of the National Autonomous University of Mexico. Photo by Hunter Knox/New Mexico Tech|
“The great success of this course was in the merger of geophysical education and research,” he said. “The students developed familiarity with digital signal processing, seismic wave beam-forming, and infrasound waveform modeling. Quantitative field volcano studies enthused students in large part because Earth processes occurred while they were watching and waiting.”
The 14 students came from varied backgrounds – geology, geochemistry and engineering dynamics. Knox, Khalsa and Johnson each said the three-week course was intense and focused. Johnson said the students were a cohesive and motivated group.
“People grabbed the bull by the horns and worked hard to get results,” Knox said. “We got up early and worked late and the energy was really high, which probably is why the class was so intense.”
"We had a lab set up at the base of the volcano,” Johnson said. “We had six computers and all the software and we just set up shop at Tungurahua. The students did an excellent job of synthesizing seismic activity and doing an array of analyses. We all sat in the lab together and worked on the data as a team.”
Students divided into small groups to analyze seismic and infrasound array data. Students identified their own projects of interest and, on the final day of the course, they presented reports at the Instituto Geofisica in Quito.
Knox was one of the few students specifically studying volcano seismology. She helped all the groups put together their presentations. Johnson said he has high hopes that the excellent quality data and impressive student motivation will lead to one or more journal publications in the coming months.
“The Instituto Geofisica handles the observation of Tungurahua,” Knox said. “We helped collect supplementary data and performed some of the basic processing that could lead to extraordinary discoveries. It was great professional development to meet Mario Ruiz and all the people at the Instituto Geofisica.”
– NMT –
By Thomas Guengerich