Scientists Stumbled Upon an Active Volcanic Eruption in a Mid-Ocean Ridge for the First Time Ever From a research submersible, scientists saw hardened lava, dead tube worms and orange flashes from an eruption in the East Pacific Rise Before the eruption, scientists saw a wide variety of ocean life around the Tica hydrothermal vent. Andrew Wozniak For the first time, scientists have witnessed an active seafloor volcanic eruption along a mid-ocean ridge. The team, exploring underwater from the research submersible Alvin, caught the rare sighting while on an expedition off Costa Rica to study the Tica hydrothermal vent. Deep sea hydrothermal vents like Tica are openings in the seafloor where heated, mineral-rich water is released into the ocean, allowing unique ecosystems to thrive around them. On April 28, the eastern Pacific waters near Tica looked just as scientists would expect: brimming with life. The team saw tube worms, mussels, crabs, fish and other animals swimming around the vent. But the next day, the landscape was barren. “My brain was trying to understand what was going on,” Andrew Wozniak, a chemical oceanographer at the University of Delaware who was on the submersible, tells Maya Wei-Haas at the New York Times. “Where did things go?” Before and After Eruption at Tica Hydrothermal Vent Watch on Eventually, Wozniak and his team noticed hardened lava covering dead tube worms and realized what they were witnessing. They were looking at the results of a volcanic eruption. In the distance, they spotted orange flashes of molten lava being released and hardening as they hit the cool water. “When we saw an orange shimmering glow in some of the cracks, it confirmed that a volcanic eruption had taken place and was still actually underway,” Alvin’s pilot, Kaitlyn Beardshear, says in a statement. After some time, though, they chose to end the dive and bring the submersible back up. “We have temperature limits to ensure the safety of the sub and its occupants,” Beardshear explains in the statement. “I kept a close eye on the temperature as we were traveling, and it kept climbing higher, until I decided it was a good idea to leave before we reached the limit.” Though the Alvin team had to cut their expedition short for safety reasons, they collected as much data as possible. They deployed scientific instruments and maneuvered bottles to gather samples for further research, says Sunita Shah Walter, a marine scientist at the University of Delaware, in the statement. “It doesn’t feel real at the moment, but to be able to observe what we saw and be able to collect samples is really mind-boggling,” adds Wozniak, chief scientist of the expedition, in the statement. “I’m so excited for my team, and I’m really excited to see what we can learn about what’s happening down there.” Underwater volcano explodes in the Pacific! Watch on Only two other underwater eruptions have been observed in real time before, and neither of those happened along an ocean ridge. But a staggering 80 percent of our planet’s volcanic and seismic activity happens on the ocean floor, making it a key target for research. Bill Chadwick, a volcanologist at Oregon State University who was not on the expedition, tells the New York Times that the sighting is a “super exciting first.” The Tica vent has been the subject of ongoing research since its discovery in 1991, when Dan Fornari, a marine geologist at the Woods Hole Oceanographic Institution, and his team witnessed the aftermath of an eruption on another Alvin dive. The team will continue to monitor the vent remotely in an effort to uncover more information about deep-sea volcanism. Geologists will examine high-resolution maps of the site to determine where exactly the eruption occurred, while chemists study how the vent’s hydrothermal fluids changed before and after the eruption and biologists trace how life returns to the area. “All of this has to do with understanding this holistic system that is Earth and ocean,” adds Fornari, who was not on the current expedition, to the New York Times. “It’s so intertwined, and it’s both complex and beautiful.” Get the latest stories in your inbox every weekday.