Into the deep

An undersea research voyage helps map an extensive area of volcanic activity

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New information gathered from the deep ocean around Kauai could eventually rewrite the story of the Hawaiian islands, say scientists returning from a monthlong research voyage.

Precision mapping of the sea floor, plus lava rock samples and photos from the ocean floor, reveal much more volcanic activity around Kauai, Niihau and Kaula islands -- and even Middle Bank -- than had been previously suspected.

Testing of the lava rock samples will reveal whether they were formed 5 million years ago, as was Kauai, or as recently as a half-million years ago.

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Kauai might have a submerged volcano to its south, a would-be sister island that never emerged above the ocean.

That theory should be proved or disproved in the year ahead as scientists test 363 volcanic rocks collected from the sea floor around Kauai, Niihau and Kaula islands and Middle Bank.

If the lava rocks from a topographic bulge south of Kauai are as old as Kauai -- 5 million years old -- scientists might have to reconsider geological history.

The area south of Kauai has long been assumed to be a massive underwater landslide that came from Kauai, said Garrett Apuzen-Ito, a University of Hawaii geophysicist who co-led a research voyage that concluded yesterday.

But if instead it was formed by a shield volcano that never came out of the ocean, "that would be the cover of Science or Nature," said Dominique Weis, a geochemist from the University of British Columbia who was on the monthlong voyage on the UH ship Kilo Moana.

Even if the lava rocks collected are much younger geologically -- less than 1 million years old -- there is still much more evidence of volcanic activity in the area covered on the voyage than had been formerly suspected, said Michael Garcia, a UH volcano geologist and voyage co-leader.

Scientists on the voyage saw dozens of signs of former volcanic activity.

"We knew there were lava flows, and we knew there were signs of volcanos around there, but we didn't realize how many," Garcia said.

"For me it was at least five times if not 10 times more than what I'd anticipated," Weis said.

"It was very successful," Apuzen-Ito agreed.

Two high-tech tools collected much of the new information on the voyage:

» The Jason 2, an unmanned robotic vehicle owned by the Woods Hole Oceanographic Institution, enabled collection of volcanic rocks, photos and video as deep as 14,000 feet underwater. By directing Jason 2's robotic arms, the scientists could choose which rocks they wanted to sample.

» Precision mapping of the sea floor with multibeam sonar and acoustic imagery created maps 6 miles wide as the ship moved along. The voyage mapped 17,000 square miles of sea floor -- 50 percent larger than the entire land mass of Hawaii. Most of that had never been mapped before.

The new, highly detailed maps will eventually be available on the UH School of Ocean & Earth Science & Technology Web site.

There were 11 Jason 2 dives, each about 36 hours long, Garcia said.

Scientists and technicians worked shifts, so someone was always watching the sea floor and directing the robotic arms to get samples of rock, he said.

One interesting sight was the numerous pillow lava formations -- most from 3 to 6 feet wide and shaped like, well, pillows. Pieces of a number of those were collected for testing to determine how old they are and their chemical composition.

Kauai teacher Linda Sciaroni was a "teacher at sea" on the cruise, communicating daily by e-mail and Internet postings with 23 classrooms on Kauai.

Students sent Sciaroni to the ship with some assignments of her own: She sent down student-decorated Styrofoam cups in the Jason submersible. The cups came back up squeezed by the deep-sea pressure to the size of thimbles -- their designs intact but miniaturized.

"Science is fun!" Sciaroni wrote in her posting for that day of the voyage.