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Collapsed undersea volcano gives view of island's birth
Hawaii Undersea Research Laboratory
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"This was a Mount St. Helen-size volcanic event"
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The recent collapse of the lava dome of the underwater volcano Loihi off Hawaii is giving scientists in a research mini-sub a close-up look at the ongoing birth of the next Hawaiian island, according to researchers just back from the site.
Two years after the largest set of earthquakes ever recorded shook the seamount, scientists returned to Loihi again this fall to repair an undersea geological observatory and conduct more chemical and biological studies. The 3rd research expedition aboard the research vessel Ka'imikai-o-Kanaloa, which began in September and continued off the big island of Hawaii through October, was sponsored by the National Undersea Research Program (NURP) and led by Alexander Malahoff, director of the Hawaii Undersea Research Laboratory at the University of Hawaii.
"This was a Mount St. Helen-size volcanic event," said Malahoff when he returned from his first expedition to the collapsed lava dome in 1997. "Pele's Dome, an area on the southern rim of the volcano that previously had been considered very stable, has simply vanished into a giant pit, which we have named the Pele's Pit Crater. What we learn from this event will have profound implications for virtually everything we now know about undersea volcanism–including the effects of volcanic carbon dioxide emissions on climate, the possible generation of tsunamis that could strike coastal areas, and the impacts on the microscopic organisms that live in and near sea floor vents."
In a series of 12 dives this fall, the NURP-funded university scientists visited the new pit, summit area and the Hawaii Undersea Geo-Observatory (HUGO). They witnessed dramatic evidence of the impact of swarms of sea floor earthquakes that struck Loihi two years ago, including the collapse of giant lava rock formations, continuing subsea tremors and landslides, and the creation of new vents spewing a mix of superheated water, dissolved minerals and massive mats of chemosynthetic bacteria that limited the scientists' visibility to a meter or less. Although temperatures at the undersea volcano have now dropped to 160 degree centigrade versus 200 degree centigrade last year, Loihi is still an active volcano, Malahoff said.
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HUGO, a permanent undersea geological observatory at Loihi, which was installed during the first expedition to monitor future volcanic activity, was in need of repairs since a leak was detected in the cable. Getting HUGO operational is a priority for scientists so that they have the ability to directly monitor the dynamic volcano versus determining its seismicity from remote stations. HUGO also represents an ideal opportunity for using the deep ocean as a laboratory for understanding ocean chemistry. Along with atmospheric influences, carbon cycling in the deep ocean is necessary for modeling and predicting global chemical and climactic change in the future.
"In terms of attracting life, Loihi is a natural bioreactor," Malahoff said. "We're awaiting colonization of the site by worms and other creatures. Loihi is also a big carbon dioxide polluter."
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Additional information about Loihi and other Hawaii Undersea Research Laboratory projects can be found at http://www.soest.hawaii.edu/HURL/hurl_research.html. HURL is one of NURP's National Undersea Research Centers whose mission is to study deep water marine processes in the Pacific Ocean. |
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