5/13/02 12:50:19 PM Pacific Daylight Time

Kent,  Thought you might find this interesting.  Especially considering
the source.  Brookhaven National Lab.

ANON

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Sometimes answers to perplexing problems are to be found in unexpected
places seemingly far afield.  My search for Tunguska related information
has gone this way and that.  Maybe in the end it is not the conclusion
which is as important as where the search has gone.  I have uncovered
something which you might find interesting.  It does have something to
do with Tunguska in a round about way, but before I explain that I need
to do some more research.

There is something going on in the Antarctic.  Clive Cussler in his book
Atlantis Found lays out a plot where a supremacist group intends to
cause the Ross Ice Shelf to disengage from the continent, which would
alter the earth's moment causing a pole-shift with dynamic
meteorological consequences.  He didn't pull that concept out of thin
air. 

Eighteen major glacier ice streams flow into the Ross Ice Shelf which is
from 975 to 2,600 feet thick.  It covers an area of 216,000 square
miles.  That is a lot of mass, but only the beginning of the issue. 
Except in a few places where the shelf is anchored to an island or an
underwater shoal, it is floating on the sea.  It might not take too much
to break it away.  Glaciologists George Denton and Terence Hughes of the
University of Maine have proffered evidence that the flow of the glacier
streams from the interior of the continent is restricted by the Ross
shelf.

The Pine Island Glacier is no longer dammed by an ice shelf.  It flows
into the Amundsen Sea at 33 feet per day, which is more than three times
the speed at which the glaciers feed into the Ross shelf.  Seismic and
radar surveys of the interior of Antarctica have revealed what may be
lakes of meltwater in places between the ice sheet and the bedrock. 
Global warming is not a conjecture.  Meltwater may be starting to
lubricate the interface which could lead to basal sliding.  Once the
sliding starts the friction will increase the melting which will
increase the sliding.  As a reference on glacier surging check out the
cover story of the New York Times, February 23, 1937-"Black Rapids
Glacier sets a speed record"…"Expert finds movement is 220 feet a day."

The Ross shelf is at the base of the Transantarctic mountain range which
is maybe 13,000 feet tall.  There is a lot of ice in the glaciers on the
way up.  If there is meltwater trickling down from the mountains at the
interface, gravity and basal sliding could push the Ross shelf out to
sea along with a lot of ice from up top.  In a geological timeframe it
could take place lickety-split.

When I heard that the Larsen-B ice shelf--a chunk of ice the size of the
state of Rhode Island--had broken away, it seemed like a harbinger.  I
hope I can get an accurate estimate of how much mass is involved and
what the best guess is for the trajectory in the circumpolar current. 
It is not a trivial issue.  It effects the surface contribution to the
moment of the earth.  Will the Antarctic ice sheet respond to conserve
the moment?  How might it respond?  I would like to do some meaningful
mental computations.  Also, what is going on in the Victoria Valley, the
Wright Valley and the Taylor Valley?  The current theory is that orogeny
is responsible for cutting off the flow of the glacier in those ice-free
valleys.  Perhaps the total answer is not that straightforward. 

I will search like a hawk for news of goings-on in Antarctica.  It is
more than just an interesting topic!  I will not be the one to cry wolf,
but neither will I play the ostrich. 


DAH   5/13/02

Geophysical interpretation of Tunguska: http://www.geocities.com/olkhov/tunguska.htm