Japanese sub
studies isles’
ocean floor
A manned submersible from
By Helen Altonn
Japan is giving geological
researchers a closer look at
the Hawaiian chain's sea floor
Star-BulletinThe world's deepest-diving manned submersible is giving scientists an up-close look at landslides and other volcanic features on the ocean floor around the Hawaiian Islands.
About 30 dives are planned in the Shinkai 6500, here from Japan with its mother ship, the R/V Yokosuka.
"That's a lot of science," says University of Hawaii geologist Julia Morgan. "We're bound to see a lot of interesting things."
The Japan Marine Science and Technology Center is sponsoring the U.S.-Japanese research program. UH and U.S. Geological Survey researchers are collaborating with the Japanese scientists.
Focus on landslides
The program began last year with the center's deepest-diving remotely operated vehicle, the Kaiko, and the research vessel Kairei. The Kaiko can operate at a depth of 17,000 feet.The submersible investigations began July 30 and will continue until Sept. 26.
"It is a really outstanding opportunity for scientists studying landslide deposits around the islands to actually go down and see the rocks in place," Morgan said.
The Shinkai 6500 is needed to reach the deepest parts of Hawaii's sea floor, previously inaccessible except by remotely operated cameras, Morgan said.
The three-person submersible is capable of diving 15,000 to 18,000 feet -- deeper than the deepest point around the islands, she said.
Scientists are using it to:
Participants include Morgan, Michael Garcia, John Smith and Alex Malahoff from UH, James Moore, Peter Lipman and Thomas Sisson from the U.S. Geological Survey, and Dave Clague, former scientist in charge of the Hawaiian Volcano Observatory and now at the Monterey Bay Aquarium Research Institute in California.Investigate the origin of giant landslides on oceanic volcanoes.
Their broad goal is to increase understanding of hot-spot magmatism and the relationship between volcanism and large-scale island landslides.
Gaining insight into the processes may help to assess potential tsunami and earthquake threats to Hawaii and the Pacific Rim from catastrophic debris avalanches, the scientists said.
Rocks that rolled
They will be diving on landslide deposits identified around the islands in recent years, Morgan said.Major areas are the giant debris fields northeast of Oahu that resulted from a Nuuanu Pali landslide more than a million years ago -- believed to be one of the largest on Earth -- and the Hilina slump, an active landslide on the southeast flank of Kilauea volcano on the Big Island.
Morgan said the scientists aim to recover rocks from the deposits to try to date them and determine which volcanoes they're from, when they formed and when they were deposited on the sea floor.
Malahoff, director of the Hawaii Undersea Research Laboratory, plans to search for deep hydrothermal vents during cruises over Loihi, Morgan said.
Dives also are planned on Puna Ridge, a submarine extension of Kilauea's East Rift Zone, and on the North Arch lava field, a very large lava flow on the deep-sea floor north of Oahu.
With data collected from the Shinkai program, Morgan said, "I think we will finally be able to put pieces together to explain what has happened as the volcano flanks have collapsed, and what is the time frame of this kind of deformation.
"One thing we don't understand is how frequently landslides move and collapse catastrophically as the Nuuanu landslide did," Morgan added. "Is Hilina likely to do the same thing? Can we get any insight comparing the two as an evolution of a single landslide?"
In drafting their research proposal, the scientists said more than 68 giant landslides have been identified on the flanks of Hawaiian volcanoes, yet they're poorly understood.
"Koolau Volcano is Hawaii's most geochemically distinct volcano and its origin remains a mystery," they said.
