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NSF PR 99-29 - April 26, 1999
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Active 14,000-Foot-High Submarine Volcano Found Near
Samoa in South Pacific
An active volcano rising more than 4,300 meters (some
14,100 feet) from the ocean floor in the Samoa Islands
has been discovered by a team of National Science
Foundation (NSF)-funded scientists, providing more
evidence in the scientific debate over the formation
of hot spot island chains. The volcano, more than
35 kilometers (about 22 miles) across at its base,
rises to within 600 meters (about 2,000 feet) of the
surface. Its peak is marked by a circular caldera
some two kilometers (about one mile) across and 400
meters (1,300 feet) deep. It is similar in size to
Mt. Whitney in California, the U.S. largest mountain
in the contiguous 48 states.
"The discovery underscores just how little we know
about the ocean floor," says Dave Epp, program director
in NSF's division of ocean sciences which funded the
research. "A major, and perhaps active, volcano was
found in an area that might be considered well surveyed."
The new volcano was discovered by Stan Hart, a geochemist
at the Woods Hole Oceanographic Institution, and colleagues.
The location had been predicted based on a 1995 earthquake
swarm in the region. The volcano has been named Fa'afafine,
a Samoan word that very loosely translated means "wolf
in sheep's clothing. It seemed an appropriate name
since the size of the volcano was a surprise," Hart
says. "The available bathymetric maps of the area
gave us no indication of what was really there on
the ocean floor."
The existing maps of the seafloor in the area, made
by satellite altimetry a few years ago and considered
the most accurate maps available, gave little indication
of the actual size of the volcano. They simply showed
a small hill-like geologic feature, one of many unnamed
features in the island chain. Hart, whose research
focuses on the formation of the earth's mantle and
the evolution of hot spots, decided to look closer
at several of the features. A detailed survey with
the research vessel Melville revealed the true size
of the volcano, and the stunning perfection of the
summit caldera, along with the first detailed information
about other features on the ocean floor around several
of the nearby islands.
Hart and his colleagues went to the area to test the
idea that the Samoa Islands are a volcanic hot spot
chain, and to prove that their formation is not principally
related to proximity to the nearby Tonga Trench, as
some earth scientists believe. The classic example
of a hot spot island chain is the Hawaiian Islands,
where what will someday be the newest island, Loihi,
is a seamount rising toward the ocean surface on the
southeast flank of the island of Hawaii. These volcanic
chains are formed as the Pacific lithospheric plate
migrates slowly northwest over a hot upwelling of
the underlying mantle. Hart believes that the Samoa
Islands chain, like the Hawaiian Islands, is indeed
such a hot spot chain, with the youngest volcano at
the end of the chain. Fa'afafine, at the far eastern
end of the Samoa Island chain, likely represents the
present location of the "hotspot."
Hart and his colleagues are planning a return trip
to the volcano, and are hoping to use a remotely-operated
vehicle or human-occupied submersible to survey the
caldera in detail, and to search for hydrothermal
hot springs and associated biota.
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