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Nafanua, Eel City, and the Crater of Death

A small but fast-growing volcano appears inside the crater of a mammoth underwater volcano off Samoa

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Sitting atop a hot spot, the 14,300-foot-high undersea volcano Vailulu?u eventually may become the next island in the Samoan chain.
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Rising 4,360 meters (14,300 feet) from the seafloor off Samoa, Vailulu'u looks like an underwater version of Mount Fuji. (Courtesy Stan Hart, Woods Hole Oceanographic Institution)
Vailulu'u sits atop a hot spot and may become the next island in the Samoa chain.
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Vailulu?u sits atop a hot spot where magma from the mantle periodically bursts through the ocean crust. It eventually may become the next island in the Samoan chain. (Illustration by Jayne Doucette, WHOI)
Maps of the caldera atop Vailulu'u, in 1999 and 2005, show a new volcano growing inside called Nafanua
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Maps of the caldera atop Vailulu'u, in 1999 and 2005, show a new volcano growing inside called Nafanu. It had reached 300 meters (1,000 feet) high, as of April 2005. (Stan Hart, WHOI)
A hydrothermal community of eels
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Scientists found hundreds of greenish-white eels, up to a foot long, swarming in a hydrothermal community near Nafanua that they called "Eel City." (Photo courtesy of Hawaii Undersea Research Laboratory)
Related Links

» 2005 Expedition to Samoa
A chronicle of the 2005 ALIA expedition aboard R/V Kilo Moana to Samoa

» Voyage to Vailulu'u
An article in WHOI Currents magazine on the discovery of Vailulu'u

In 1999, WHOI geochemist Stan Hart was co-chief scientist of a joint WHOI-Scripps Institution of Oceanography expedition that discovered and mapped Vailulu’u—an active volcano rising 4,360 meters (14,300 feet) from the seafloor of the Pacific Ocean. Resembling Mount Fuji, Vailulu'u sits atop a hot spot, fueled by magma erupting from the mantle. The hot spot will eventually build the volcano high enough to become the next island in the Samoan chain.

In April 2005, Hart and international colleagues returned to Vailulu’u to make more astonishing discoveries. They found a dome-shaped volcanic cone—growing inside Vailulu’u’s milewide caldera—that didn’t exist when the scientists last visited in 2001. This new volcano, named Nafanua after the ferocious Samoan goddess of war, stood 300 meters (1,000 feet) high.

Diving in the National Oceanic and Atmospheric Administration’s submersible Pisces V, scientists explored the turbid waters surrounding Nafanua, where vigorous venting of hot, mineral-rich fluids creates a volcanic “fog.” The area was covered with thick yellow mats of microbes that thrive on chemicals spewing from volcanic hydrothermal vents. Some areas were filled with large bubbles, fizzing like seltzer.

The scientists also found hundreds of greenish-white eels, up to a foot long, which emerged from rock caves and crevices and swarmed around cavernous rock pillars. The scientists named this novel hydrothermal community “Eel City.” In contrast, the scientists also found a possibly toxic area that was devoid of life at the bottom of Vailulu’u’s crater, which they dubbed the “Crater of Death.”

The research was funded by the National Oceanic and Atmospheric Administration, the National Science Foundation, the Australian Research Council, and the WHOI Deep Ocean Exploration Institute.



Posted: September 27, 2005

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