Hoping to learn more about undersea volcanoes, scientists sent a camera-equipped submarine down to take a look. They got more than they bargained for, witnessing a deep-sea eruption.
"At first we really didn't understand what was going on," said Bob Embley, chief scientist on the mission, which involved nearly three dozen researchers.
"We were seeing billowing clouds coming up and turning yellow. There was sulfur and rocks were flying out," said Embley, an oceanographer with the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory. "We realized we were the first to witness a deep-sea volcano during an eruptive episode."
He added: "The amazing thing is we were able to sample it. ... It would not have been a good place to be in a manned submersible."
Caustic material damages camera
The material from the eruption is still being studied. It was highly caustic, Embley said, damaging the camera lenses even though the robotic submarine was quickly backed away from the volcano.
The volcano, with a rim 1,800 feet (550 meters) below the sea surface, was named "Brimstone Pit" by the scientists.
The discovery, northwest of the island of Rota in the Northern Mariana Islands, came during a 21-day voyage to study undersea volcanoes in the western Pacific. Nearly 70 percent of the world’s volcanoes are undersea, Embley said in a telephone interview.
Also on the team was Bill Chadwick, a volcanologist with the Cooperative Institute for Marine Resources Studies at Oregon State University. "We were just going from one incredible event to the next, seeing things we had never witnessed before," he said.
Studying geology and marine life
The trip, which ended April 18, included studies of geology and marine life in both deep and shallow areas.
In upper levels of the oceans, life draws energy from sunlight. Because deeper areas are dark, life there gets its energy from chemicals released by hot ocean vents.
At a bit more than 600 feet (180 meters) deep the researchers found a zone where the two overlap, finding both light-loving and chemical-using life forms, Embley said.
"The biologists were amazed to see this ... two of earth's ecosystems overlapping. That is very unusual," he said. "We don't know the implications."
Scientists from the United States, Canada, New Zealand and Japan participated in the work and took home samples to study.
Carbon dioxide released
In another area of the Mariana Trench, the researchers found bubbles of liquid carbon dioxide being released into the sea, enlarging up to a thousand times and turning to gas as they drifted upward in the sea.
Steve Hammond, chief scientist for NOAA's Office of Ocean Exploration, termed the find "a natural laboratory where the effects of carbon dioxide on marine organisms can be studied."
The liquid form of carbon dioxide is present due to the great depth and the resulting pressure at the site. At 5,263 feet, about a mile (1.6 kilometers) deep, the pressure from the water column is 160 times more than the air pressure at sea level.
A similar effort a year earlier gathered preliminary data on the area near Guam and the Mariana Islands. Next year, Embley said, the research will focus on underwater volcanoes north of New Zealand.
Mysteries under the sea
He pointed out that although most of the planet is covered with water the undersea regions have not been thoroughly studied in the past.
"Out there on our own planet there are volcanoes erupting under the ocean, putting chemicals into the ocean, interchanging gases (into the water and air), affecting biology. We should know about these things," Embley said.
"Microbes in extreme environments produce enzymes that could be of medical use," he added.
The research was funded by the NOAA Ocean Exploration Program and the Natural Science and Engineering Research Council of Canada.