27 Jul 06 - "A new type of volcano may be heating up the floor of the western
Pacific Ocean," says this article posted on National Geographic News and on
Yahoo. (If you’ve read my book or tracked my web site, you know that’s
what I’ve been saying for years -- that underwater volcanoes are heating
the seas.)
"Scientists suspect the new volcanoes occur at cracks in tectonic plates caused
by stress as the plates slide past each other.
"A group of small volcanoes called petit spot volcanoes has been discovered far
from the tectonic-plate boundaries (like mid-oceanic ridges) that often spawn
volcanoes, earthquakes, and other geologic activity.
Geoscientist Naoto Hirano's team believes that the source of these volcanoes is
melted rock from the upper mantle, which has been squeezed through cracks in
the tectonic plate above.
"This type of [activity produces] tiny volcanoes, possibly now active, on the old,
cold subducting Pacific plate," said Hirano from his office at the Scripps Institution
of Oceanography in La Jolla, California. "This petit spot volcano theory suggests
that this type of eruption can occur wherever the oceanic plate is flexed."
"These small volcanoes may be widespread on ocean floors where the mantle just
under the crust is squeezed out by tectonic forces when one plate moves under
another, the researchers explained.
Underwater Volcanoes Heating the Pacific Ocean
"Dubbed "petit spots," these new types of volcanoes are difficult to spot using
satellite technology. Specific geophysical and sampling expeditions would have
to be carried out in order to locate them," Hirano explained.
Source:
http://www.iceagenow.com/Underwater_Volcanoes_Heating_Pacific_Ocean.htm
Scientists working in the southern Atlantic Ocean have found a 407 °C hydrothermal vent, the hottest yet known on an ocean floor. Expedition leader Andrea Koschinsky of International University in Bremen , Germany , and her team found the hydrothermal vent just south of the Equator on the Mid-Atlantic Ridge at a depth of 2,990 metres.
The vent is located on the Mid-Atlantic Ridge, where the African and the South American continental plates are moving apart at the relatively sedate rate of 3.2 cm a year. In the Pacific, by comparison, the Pacific and Nazca plates are speeding apart at some 15 cm per year.
The accepted wisdom has been that faster plate movement leads to more volcanic activity at the spreading site, says Colin Devey, a member of the team and a geologist at Leibniz Institute of Marine Sciences in Kiel , Germany . The discovery of this hotspot will change people's thinking, he says. "The accepted wisdom is wrong."
see also:
http://www.iceagenow.com/Ocean_Warming.htm