NEWPORT, Ore. - A team of scientists from Oregon State University and North Carolina State University is heading toward the western Pacific Ocean to recover a series of hydrophones they deployed last year to monitor an erupting undersea volcano called West Mata.
While there, the researchers will deploy an undersea glider to collect water column data from the volcano and record more sounds of its eruption.
"We're also retrieving 16 hydrophones spread throughout the southern Lau basin, where we recorded a massive near-surface volcanic eruption in March 2009 that was close to the island of Tonga," said Robert Dziak, an OSU marine geologist based at the university's Hatfield Marine Science Center in Newport. "We also recorded sounds of the magnitude 8.2 earthquake that produced the tsunami that hit American Samoa in September of last year."
The team will leave Fiji on April 16 aboard the R/V Kilo Moana, operated by the University of Hawaii, and return April 26. During their expedition, the scientists will be in contact with 30 OSU students taking an online course taught by Dziak on earthquakes.
The hydrophone data provides scientists with an in-depth look at the process of undersea volcanic eruptions. From that data, Dziak also will be able to approximate the total weight of carbon dioxide gas emitted from West Mata, estimated at several megatons annually.
"No one is quite sure how many volcanoes are erupting beneath the surface of the ocean at any one time," Dziak said, "but since about 75 percent of the world's volcanic activity occurs underwater, it could be significant. This will give us a better handle on what role these volcanoes may play in the global carbon exchange."
West Mata is a 3,000-foot high seamount discovered in the fall of 2008 that has continually erupted, producing boninitic lava in big bubble bursts accompanied by huge plumes of volcanic debris and lava flows. It was the focus on much media attention because it was the deepest volcanic eruption ever directly observed by scientists and the first to have sound recorded on location.
Haru Matsumoto, an OSU engineer who designs undersea instrumentation, will deploy an autonomous glider to "fly" over the summit of the West Mata volcano and record additional sounds. The glider, provided by Bob Embley of the NOAA/Pacific Marine Environmental Laboratory in Newport, will also include a volcanic plume sensor to gauge how much rock debris is hurled into the ocean by the eruption.
The OSU scientists are international leaders in the use of undersea hydrophones to analyze earth processes. Dziak and his colleagues at the Hatfield Marine Science Center continually monitor earthquakes through a system of hydrophones located on the ocean floor. The network - called the Sound Surveillance System, or SOSUS - was used during the decades of the Cold War to monitor submarine activity in the northern Pacific Ocean. As the Cold War ebbed, these and other unique military assets were offered to civilian researchers performing environmental studies, Dziak said.
Matsumoto also has developed portable hydrophones, which he and Dziak have deployed in Antarctica and the Southern Ocean to listen for seismic activity in that region. The sensitive hydrophones also have recorded a symphony of sounds revealing not only undersea earthquakes, but the movement of massive icebergs, and vocalizations of whales, penguins, elephant seals and other marine species.
OSU scientists Susan Merle and Ron Greene also will be aboard the Kilo Moana immediately following Dziak's expedition for a NOAA-funded project that will further investigate West Mata. The OSU scientists will use a deep-sea camera system and collect water samples to further map the volcanic impact.
The April 2010 expedition is funded by the National Science Foundation and the NOAA Vents Program. Blogs of the cruises are available at http://web.me.com/drbohnen/Lau_AUH/Home.html and http://laueruptions.blogspot.com
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Bob Dziak, 541-867-0175