For some, exploring volcanoes under thousands of feet of frigid water might seem impossible. For Robert Sohn the challenge of unlocking the volcanic secrets on the Arctic Ocean’s sea floor is a calling. Sohn is an associate scientist at Woods Hole Oceanographic Institute (WHOI) who mixes volcanology and the study of hydrothermal processes with the development of autonomous underwater robots specially suited to weather extreme conditions.
As a kid growing up in Indiana, Sohn wasn’t particularly interested in volcanoes. His curious nature pointed him to science, and he earned a bachelor’s in mechanical engineering. It wasn’t until graduate school that his interest in volcanoes erupted.
“I’ve always had a kind of gearhead interest in instruments and machines and I’ve been studying underwater volcanoes since I was in graduate school. So it was a confluence of those two lines of training that led me to where I am now,” Sohn said.
Sohn’s interest in volcanoes and technology has led him to the bottom of the Arctic Ocean and to some unexpected discoveries.
The Surprise at Gakkel Ridge
In 2001 researchers with the Arctic Mid-Ocean Ridge Expedition (AMORE) to Gakkel Ridge detected thermal characteristics in the water column that indicated volcanic plumes almost everywhere along the ridge.
“This was astonishing to hydrothermal researchers like myself!” Sohn explained. “This is the slowest spreading tectonic plate boundary anywhere on Earth. So it should have very limited amounts of hydrothermal circulation. Yet the sensors were returning signals from everywhere. This was a very enigmatic result. We wanted to explore the sea floor with robots to try to find these volcanoes and learn more.”
In 2007, with funding from the National Science Foundation, the National Aeronautics and Space Administration and Woods Hole Oceanographic Institution, Sohn along with an international team of scientists launched the Arctic Gakkel Vents Expedition (AGAVE) to pick up where AMORE left off.
Using specially designed autonomous underwater vehicles and a state-of-the-art camera and sampling system developed by Sohn and other WHOI engineers and scientists, the team uncovered evidence of violent volcanic explosions that shocked the scientific community.
“The conventional wisdom for the longest time had been that volcanoes under 4,000 m of water were under such high pressure there could never be enough gas in the magma to make them explode,” he explained.
AGAVE also resulted in the discovery of the Asgard volcanic chain; the first observation of orange-yellow cotton candy-like microbial mats thriving on the volcanoes’ surface; a suite of mapping data; and the discovery of basaltic glass fragments that cover large areas of the Arctic Ocean’s floor. Three years on, scientists are still working to analyze the full breadth of physical and biological data from the mission.
Sohn’s quest to explore and study volcanoes has taken him all over the world. He’s researched volcanic activity throughout the Caribbean, Atlantic, and Pacific Oceans, as well as Hawaii, Costa Rica, Yellowstone National Park, Cyprus and a host of other locations. But the challenge of studying volcanoes covered by 4 km of frigid water and permanent layers of ice has always attracted him to the Arctic.
“It probably makes my life more difficult, but I’m always intrigued by a good challenge,” Sohn laughed. “And for the kind of research I do, the Arctic is the ultimate challenge.”
He’s also drawn to the Arctic because of the potential to make new, exciting scientific discoveries. Because the Arctic is so unexplored and there’s so little data available to volcanologists, the region is ripe for unexpected discoveries. And AGAVE illustrated that point perfectly.
“The coolest AGAVE discovery was finding the exploding volcanoes. It was totally unexpected,” he said. “It was like a scientific treasure chest at the bottom of the Arctic Ocean, and we had to figure out how to open it. Plus opening that treasure chest was a huge technological challenge.”
The next great challenge for Sohn: exploring life under the Antarctic ice shelves. He is currently working on a proposal to develop autonomous underwater vehicles to study the biological communities under the Ross Ice Shelf.
For more information about Robert Sohn and his research, visit: http://www.divediscover.whoi.edu/expedition11/index.html