Tracking the ups and downs of Axial Seamount

Story by Marley Parker

Bright lights illuminate rain drops splattering across the back deck of R/V Atlantis. It’s just after 2:00 a.m., but the entire ROV team (and most of our science team) is awake and ready to go to work. Expedition Leader Akel Kevis-Stirling lifts a radio to his ear as the voice of Captain Derek Bergeron crackles through the speaker.

“You are clear for launch.”

“Copy that,” Akel says. “Launching Jason.”

The 11,000-pound remotely operated vehicle (ROV) Jason rises slowly into the air and glides smoothly over the port rail of the ship. While launching Jason is a routine activity aboard Atlantis, this particular launch brings a sense of relief for the whole team. After dealing with a mechanical setback with the ROV winch at the start of this expedition, we are thrilled to finally get Jason in the water and begin our work on the seafloor.

We are currently 300 miles off the coast of Oregon, floating above the Juan de Fuca mid-ocean ridge spreading center. A mile below us is Axial Seamount, the most active volcano in the Pacific Northwest. With support from the National Science Foundation, Chief Scientist Bill Chadwick has brought this team out here to deploy equipment that will capture Axial’s next eruption. 

An hour after the launch, several members of our science team crowd into the control van to watch the live feed from the ROV cameras. As the seafloor comes into view on the monitors, a buzz of excited chatter fills the room-and grows louder when Jason glides towards a hydrothermal vent.

These unique geothermal features evoke imagery of the underworld, rising up from the seafloor to release a steady stream of super-heated water saturated with dissolved minerals from within the ocean crust. Fittingly, this first vent is named “Inferno” (and our next stop is “Hell”).

Chief Pilot Tito Collasius maneuvers the right arm of Jason to position a temperature probe in the center of the shimmering hot water. In the back row of the control van, Dax Soule and Hikari Oshiro make predictions about what the exact temperature might be.

“I think it’ll go to 292 degrees,” Dax says.

Hikari guesses 275 degrees. We all watch the monitor as the temperature climbs-quickly surpassing 260, then 280, and finally landing at 293 degrees Celsius, or 559 degrees Fahrenheit.

The science team logs the temperature reading as Chief Scientist Bill Chadwick confers with Tito about their next task.

Probing hydrothermal vents on the seafloor is undoubtedly a phenomenal way to spend a workday, but for folks who don’t specialize in submarine volcanism, the perennial question is: “Why are you doing this?”

Posing questions about a volcano erupting on the seafloor may seem akin to asking about a tree falling in the forest. If no one is around to hear it, does it make a sound? And who cares?

In the case of Axial, we are listening to every sound it emits – it’s the most heavily monitored submarine volcano in the world. Scientists regularly receive real-time data from Axial through a network of seafloor instruments connected to shore by a fiber-optic cable, part of a larger effort called the Ocean Observatories Initiative (OOI).

But those instruments cannot characterize the entire volcano. Part of our work out here includes deploying bottom pressure recorders, which can give us precise measurements from more areas of the caldera.

“We have a better idea of what the magmatic system looks like here than just about anywhere,” says Scott Nooner.

“By studying the system here, we can learn a lot about how eruptions are triggered and what the build-up to eruptions looks like,” Bill says. “And then we can apply those lessons to other volcanoes around the world.”

Between eruptions, the magma chamber within Axial begins refilling, a process that volcanologists refer to as inflation. This slow rise over time causes the seafloor to uplift, a transformation captured by our bottom pressure recorders.

We are also tracking this change with AUV Sentry, a powerful deep sea vehicle that can work in tandem with ROV Jason.

“This is a different way to use Sentry-instead of mapping unexplored parts of the seafloor, we are repeating past surveys to look for changes,” Bill says.

In other locations on the seafloor, this type of fluctuation would be non-existent or too miniscule to measure, but the depth changes at Axial are significant-up to 10 feet between one eruption and another.

“We’ve been mapping at Axial with various AUVs since 2006,” Dave Caress says. “At the conclusion of this expedition, we will have 89 surveys altogether-about a third of those are from Sentry.”

The original goal of AUV operations was to cover the area to give researchers a visual of different features at Axial.

“Now we’re moving from mapping the seafloor to measuring change on the seafloor,” Dave says. “It’s a fundamental tool to understand different lava morphologies and to see the volcanic history of hundreds of eruptions.”

“We’ve gone from intermittent observations to continuous and comprehensive monitoring of the entire volcanic system,” says Jeff Beeson.

Since its last eruption in 2015, the magma chamber within Axial has re-inflated to more than 90% of its pre-eruption level.

“We learn the most from volcanoes by catching them in the act,” Bill says. “A big part of our work here is to ensure everything is in place for the next eruption-which we think will happen in the next few years.”

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Bill Chadwick is a research professor at Oregon State University.

Dax Soule is an assistant professor at Queens College.

Hikari Oshiro is an undergraduate student at Rutgers University majoring in marine biology.

Dave Caress is a principal engineer and head of the Seafloor Mapping Lab at Monterey Bay Aquarium Research Institute (MBARI).

Scott Nooner is a professor of geophysics at University of North Carolina at Wilmington.

Jeff Beeson is an assistant professor at Oregon State University.

The cabled observatory at Axial Seamount is part of the Ocean Observatories Initiative (OOI) which is supported by the National Science Foundation and operated by the University of Washington.

ROV Jason and AUV Sentry are operated by the National Deep Submergence Facility, which is housed at the Woods Hole Oceanographic Institution and supported by the National Science Foundation and the Office of Naval Research.