Under the Sea

A great deal of Earth’s volcanic activity takes place on the ocean floor. 

However, these events are hard to spot, with only two underwater eruptions ever being observed in real time – until now. 

Scientists recently witnessed another active seafloor volcanic eruption that was also the first to be seen to happen along a mid-ocean ridge. 

The team was exploring in the research submersible Alvin and caught the eruption while studying the Tica hydrothermal vent off the coast of Costa Rica, Smithsonian Magazine explained. 

Hydrothermal vents like Tica are deep-sea openings in the ocean floor that release heated, mineral-rich water, creating the conditions for unique ecosystems to thrive. In late April, scientists found the eastern Pacific waters near Tica exactly as they expected them, bursting with marine life.  

The next day, however, the landscape was empty.  

“Tica was barren,” Andrew Wozniak, chief scientist of the expedition, said in a statement, shocked by what he found. “Almost completely gone.” 

Then the team found hardened lava covering dead tube worms and realized they were witnessing the aftermath of a volcanic eruption.  

In the distance, they could see orange sparkles of molten lava being released and hardening when hitting the cool water.  

“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,” said Wozniak. “I’m really excited to see what we can learn about what’s happening down there.” 

After some observation and data collection for further research, researchers decided to end the dive.  

“We have temperature limits to ensure the safety of the sub and its occupants,” the submersible’s pilot, Kaitlyn Beardshear, said in a 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.” 

Now, the team will monitor the vent remotely to learn more about deep-sea volcanism. Also, geologists will attempt to pinpoint the exact location of the eruption, chemists will focus on the change in the vent’s hydrothermal fluids before and after the event, and biologists plan to examine how marine life returns to the area afterward.