WILMINGTON — Three hundred miles off the coast Oregon – and nearly a mile down – the Axial volcano has erupted twice in the last five years. Dr. Scott Nooner is trying to understand this increase, a dramatic rise in activity since the volcano’s earliest recorded eruption in 1998.
Nooner, who teaches marine geology at University of North Carolina Wilmington, has been studying the volcano for 17 years – since that first recorded eruption. His research involves monitoring minute changes in the seafloor, indicating the increasing amount of magma beneath the surface – and thus the increasing pressure around the magma chamber.
This involves some delicate deep-sea work, using Remotely Operated Vehicles (ROVs). Scientists, including Nooner, placed sensitive equipment around the Axial caldera to measure changes is seismic activity, water pressure and the tilt of the seabed (which changes as the ocean floor lifts up in a dome on top of the magma chamber beneath it).
After isolating what Nooner calls “a threshold, kind of a breaking point,” he was able to predict an eruption in 2015.
“The seafloor was lifting up, like an inflating balloon, after the 1998 eruption. But it was doing it at a slower rate, maybe fifteen centimeters a year. After the 2011 eruption, the seafloor collapsed down rapidly, essentially deflating as the magma became a lava flow on the seabed. The new rate of expansion as magma started collected again was much quicker. But we were expecting the same threshold, and we were able to predict the eruption about seven months out.”
The Axial seamount, located on the rift where the Juan de Fuca plate pulls away from the Pacific plate, is something of a natural laboratory, “it’s probably the most well studied underwater volcano,” said Nooner. “It’s not simple, but it terms of volcanic structures its a simpler system. It’s fed by a rift system, where the plates are pulling apart, and the crust in thinner, with a simpler magma chamber than a volcano on land. We’re just starting to get a good picture of how this volcano works.”
Nooner has made numerous trips to the waters of the Pacific Northwest, frequently taking UNCW graduate students with him. Most recently he has traveled on two U.S. Navy owned research ships, the Thomas G. Thompson (operated by the University of Washington’s School of Oceanography) and Atlantis, its sister ship. Atlantis is also the maritime home to the famed ALVIN, the manned, deep-sea vehicle. Nooner has made several descents in ALVIN, calling it “very cool.”
The benefits of the studying the underwater volcano are two-fold. First, Nooner said, “there are some things you just couldn’t do on land. We’re at sea, and we can keep the boat exactly where we want it above the volcano, and remotely lower equipment and sensors down into the caldera. We’re relatively level and we’re protected from immediate dangers of the caldera – because it’s underwater.”
Secondly, the volcano’s remote location – its depth underwater and distance from shore – mean it poses no danger, even to coastal cities in Washington or Oregon. In one sense, this means that Nooner can take a purely scientific approach to eruptions without worrying about property damage.
“We can look forward to an eruption, without worrying about evacuating a city, just as a scientific event,” he said.
This does not mean that Nooner’s job is without its challenges. Extreme pressure will crush anything that is not properly constructed and corrosion gives electronics a much shorter lifespan.
“Electricity and salt water, it’s not a good combination if you don’t do it right,” he said.
Additionally, many forms of marine life – from the bacteria that thrives around hydrothermal vents to the octopuses frequently seen on remote cameras – seem to enjoy having novel surfaces to explore.
“You put anything down on the seafloor, the biology is going to try and make use of it,” he said.
Nooner plans to return to the Axial seamount in 2017. His ultimate goal is to extrapolate what he has learned at Axial and use it to understand volcanic activity elsewhere. He is currently studying fault activity in Eastern Africa and hopes to visit the Aleutian island chain, further north in the Pacific from Axial.
“We can use what we’ve learned to study Kīlauea, in Hawaii and Krafta, in Iceland,” he said. “And then different types of volcanic structures, like Mt. Rainier and Mt. St. Helens. Volcanic activity that has a little more impact of populated areas.”
Below: Video from the 2015 expedition to the Axial volcano. (Credit Scott Nooner, University of North Carolina at Wilmington, Bill Chadwick, Oregon State University, and ROV Jason, Woods Hole Oceanographic Institution.)
