Deep vents found in rarely explored Mariana Back-arc

Photograph of the seafloor showing the edge of a recently erupted lava flow (dark in lower half of image) that was discovered during the R/V Falkor expedition. (SOI/AUV SENTRY)

Photograph of the seafloor showing the edge of a recently erupted lava flow (dark in lower half of image) that was discovered during the R/V Falkor expedition. (SOI/AUV SENTRY)

A Schmidt Ocean Institute research vessel has increased the number of known hydrothermal vent sites from three to seven after discovering four new areas of activity in the Marianas Back-Arc, an area west of the Mariana Trench where tectonic plate are spreading and underwater volcanic activity are concentrated.

One of these newly discovered vents is among the deepest ever found, at a depth of 4,230 meters or 13,900 feet, according to the Schmidt Ocean Institute in statement this month. There are about 700 vent sites known globally and only three other vents are known to extend deeper than the newly discovered vents.

Scientists aboard the 28-day expedition on the R/V Falkor also discovered a recently erupted lava field that is “likely only a few months old.”

According to the institute, the region probably only experiences eruptions no more than once a century, making the 400 feet long lava flows discovered an exceptional find. Scientists were able to observe cloudy warm water leaking through the still-cooling lavas.

“When [the autonomous underwater vehicle] Sentry came back on board and we looked at the photo survey our jaws just dropped,” said co-chief scientist Bill Chadwick. “There was this brand new lava flow on the sea floor, which looks like it could have come out yesterday…It’s in a fascinating part of the Back-arc with whopping hydrothermal signals.”

NOAA Pacific Marine Environmental Laboratory Cooperative Institute scientists Dr. Joe Resing, from the University of Washington, and Chadwick, from Oregon State University, led the monthlong expedition.

Scientists also used multi-beam sonar and chemical and optical sensors to hunt for new hydrothermal oases on a track that explored a 400-mile stretch of seafloor in the area of the Marianas Trench Marine National Monument, the institute said in their statement.

Dennis B. Chan | Reporter
Dennis Chan covers education, environment, utilities, and air and seaport issues in the CNMI. He graduated with a degree in English Literature from the University of Guam. Contact him at dennis_chan@saipantribune.com.

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