Scientists First Observed Volcanic Eruptions at Deep-Sea Ridges

Andrew Wozniak, a chemical oceanographer at the University of Delaware, found it difficult to comprehend the scene before him. Dr. Wozniak was stationed at the bottom of the Pacific Ocean, nearly 1.6 miles below the surface, aboard Alvin, the research submersible. As far as his eyes could scan, there lay a nearly desolate expanse of jet-black rock.

Just a day prior, this area was alive with the bustling activity around the Tika hydrothermal vent, situated about 1,300 miles west of Costa Rica. The rocky seabed was home to a vibrant ecosystem, teeming with life. Bright crimson-tipped giant tubeworms intertwined with clusters of mussels, encapsulated in a tapestry of thriving organisms. Crustaceans scuttled about, while ethereal white fish glided gracefully in search of their next meal.

Now, however, only a solitary cluster of dead tubeworms remained amid the darkened landscape. The vivid orange glow of molten lava flickered through the rocks, and a fine mist clouded the water.

“My mind was racing to grasp what had transpired,” Dr. Wozniak said. “Where did everything go?”

Then it dawned on him: he and his fellow explorers had observed the aftermath of a volcanic eruption that had obliterated a once-thriving ecosystem beneath a fresh layer of lava.

This marked the first time scientists had directly witnessed a clear eruption along a ridge in the Central Ocean, a volcanic mountain chain stretching approximately 40,000 miles globally. Baseball seams signify the boundaries of tectonic plates that, when separated, can trigger volcanic eruptions, creating new crust and layers of Earth’s structure beneath the ocean. Approximately 80% of Earth’s volcanic activity occurs at the seafloor, predominantly along the mid-ocean ridge. Before this recent observation, only two underwater eruptions had been documented, neither occurring along the mid-ocean ridge, noted Bill Chadwick, a volcanologist from Oregon State University who was not part of the research team.

“This is an incredibly exciting first,” he remarked.

Such observations provide an invaluable opportunity for scientists to explore fundamental processes of our planet: the formation of new seabeds and their dynamic influence on marine chemistry, ecosystems, microbial life, and beyond.

“Experiencing it in real time is an extraordinary gift. I’m truly envious,” said Deborah Kelly, a marine geologist at the University of Washington who did not participate in the research.

Dr. Wozniak and his team set sail on the R/V Atlantis before diving into the Alvin submersible. Their initial mission was to examine the carbon emissions from Tika’s vents, funded by the National Science Foundation. Hydrothermal vents act as planetary piping systems, discharging heated seawater from the seabed and facilitating the transport of heat and chemicals from within the Earth, thus regulating marine chemistry and sustaining a unique community of deep-sea organisms.

Tuesday morning’s dive commenced like any other. Alyssa Wentzel, an undergraduate from the University of Delaware, accompanied Dr. Wozniak in Alvin, sharing her excitement about descending into the ocean’s depths for a 70-minute journey to the seabed. As the lights dimmed, bioluminescent jellyfish and tiny zooplankton danced in the water.

“It felt magical,” she remarked. “It truly leaves you speechless.”

However, as they neared the site, the temperature gradually increased, shrouding the area in a dark haze. The seabed’s usual dull gray and brown tones were replaced with tendrils of glassy rock, an outcome of rapid cooling when lava makes contact with cold water.

As the particles clouded Alvin’s view, Caitlyn Biadshire, a pilot from Woods Hole Oceanographic Institution, guided the submersible while monitoring the temperature closely, concerned about the safety of the submersible and its crew. Ultimately, the pilot decided a retreat was necessary.

“It was a breathtaking sight,” they reflected. “Everything I observed just days earlier has been wiped away. I feel incredibly fortunate to have been there within hours of the eruption.”

After returning to the ship, the team learned that a sensitive microphone, known as a Hydrophone, was onboard the Atlantis and had recorded a series of low-frequency rumbles and crackling sounds reminiscent of a campfire.

This represented the third known eruption at the Tika Vent since its discovery in the 1980s. For decades, marine geologist Dan Fornari and his colleagues have closely monitored the site, tracking changes in temperature, water chemistry, and other factors. By combining these analyses with models of seafloor diffusion, they predicted an eruption was imminent, forecasting it could happen either earlier this year or in the previous year.

In 1991, they reached Tika shortly after an eruption began. Although it may have still been active, they lacked visual confirmation of the lava. This time, he asserted, there was no doubt about what the Alvin crew witnessed. “This was the closest we’ve ever come to witnessing the onset of an eruption,” he stated.

The team continues its research into volcanic activity. Due to safety considerations, they are now collecting data and capturing images from the Atlantis remotely.

This data aids researchers in unraveling the mysteries of deep-sea volcanism and its significance within marine ecosystems. “It’s all connected to understanding the overall system of Earth and the ocean,” Dr. Fornari stated. “The relationship is both intricate and beautiful.”