[Infowarrior] - Huge 'Ocean' Discovered Inside Earth

[Richard Forno]

      http://www.livescience.com/environment/070228_beijing_anomoly.html

Huge 'Ocean' Discovered Inside Earth
By Ker Than
LiveScience Staff Writer
posted: 28 February 2007
01:28 pm ET
    

Scientists scanning the deep interior of Earth have found evidence of a vast
water reservoir beneath eastern Asia that is at least the volume of the
Arctic Ocean.

The discovery marks the first time such a large body of water has found in
the planet¹s deep mantle.

The finding, made by Michael Wysession, a seismologist at Washington State
University in St. Louis, and his former graduate student Jesse Lawrence, now
at the University of California, San Diego, will be detailed in a
forthcoming monograph to be published by the American Geophysical Union.

Looking down deep

The pair analyzed more than 600,000 seismograms‹records of waves generated
by earthquakes traveling through the Earth‹collected from instruments
scattered around the planet.

They noticed a region beneath Asia where seismic waves appeared to dampen,
or ³attenuate,² and also slow down slightly. ³Water slows the speed of waves
a little,² Wysession explained. ³Lots of damping and a little slowing match
the predictions for water very well.²

Previous predictions calculated that if a cold slab of the ocean floor were
to sink thousands of miles into the Earth¹s mantle, the hot temperatures
would cause water stored inside the rock to evaporate out.

³That is exactly what we show here,² Wysession said. ³Water inside the rock
goes down with the sinking slab and it¹s quite cold, but it heats up the
deeper it goes, and the rock eventually becomes unstable and loses its
water.²

The water then rises up into the overlying region, which becomes saturated
with water [image]. ³It would still look like solid rock to you,² Wysession
told LiveScience. ³You would have to put it in the lab to find the water in
it.²

Although they appear solid, the composition of some ocean floor rocks is up
to 15 percent water. ³The water molecules are actually stuck in the mineral
structure of the rock,² Wysession explained. ³As you heat this up, it
eventually dehydrates. It¹s like taking clay and firing it to get all the
water out.²

The researchers estimate that up to 0.1 percent of the rock sinking down
into the Earth¹s mantle in that part of the world is water, which works out
to about an Arctic Ocean¹s worth of water.

³That¹s a real back of the envelope type calculation,² Wysession said.
³That¹s the best that we can do at this point.²

The Beijing anomaly

Wysession has dubbed the new underground feature the ³Beijing anomaly,²
because seismic wave attenuation was found to be highest beneath the Chinese
capital city. Wysession first used the moniker during a presentation of his
work at the University of Beijing.

³They thought it was very, very interesting,² Wysession said. ³China is
under greater seismic risk than just about any country in the world, so they
are very interested in seismology.²

Water covers 70 percent of Earth¹s surface and one of its many functions is
to act like a lubricant for the movement of continental plates.

³Look at our sister planet, Venus,² Wysession said. ³It is very hot and dry
inside Venus, and Venus has no plate tectonics. All the water probably
boiled off, and without water, there are no plates. The system is locked up,
like a rusty Tin Man with no oil.²