Ice station on the edge of the abyss

December 10, 2015 5:41 am
Rescue mission under way for Antarctic research base standing in fissure’s path.
 

Halley VI Research Station is 8km from the growing crack. Photo / Nasa

It has all the hallmarks of a Hollywood disaster movie.
A
crack along the Antarctic ice-shelf is making its way towards an
isolated research station, threatening to plunge the scientists on board
into the frozen seas.
As the fissure moves ever closer, scientists at headquarters mount a desperate rescue mission.
The grim scenario is all too real for the 35 men and women stationed on Halley VI.
The
British Antarctic Survey (BAS) research station, which opened in 2013,
is located on the Brunt ice shelf, a floating slab of ice up to 250m
thick attached to the Antarctic landmass and extending out into the sea.
The
station’s eight space-age modules are under threat from an ice crack
called Chasm 1, a massive fissure more than 49m deep, 29km long and
almost 1km wide.

Chasm 1 was dormant until 2012, when satellite measurements
confirmed it had started to grow. Worse still, it was discovered the
crack is extending in the direction of Halley VI at a rate of 1.5km a
year and is now just 8km from the base.
An operation has now been
launched to move the base before the situation reaches a point of no
return – such as a huge chunk of ice breaking off, in a process known as
glacial “calving”, with the ice-station stranded on top of it.
Hilmar
Gudmundsson, a glaciologist with the BAS, said: “We don’t know what
will happen. It might stop growing, but we can’t exclude the possibility
of a big calving event.”
Taking advantage of the Antarctic
summer, which follows nine months of winter isolation, preparations are
now in hand to move Halley VI.
In the months ahead, bulldozers
will be brought in by ship to tow the modules to a new location, about
30km away from Chasm 1. The operation is expected to be completed in a
year’s time.
Adam Bradley, Halley’s station leader, warns that
even small slopes could pose an insurmountable obstacle in moving the
heavy modules and a route will have to be carefully plotted before the
operation begins.
“One of the jobs is to define the maximum slope we can tow these things up,” said Mr Bradley.
All
five of Halley VI’s predecessors have been abandoned after becoming
buried in snow, so the danger to its continued operation is all too
real.
Crevasses and chasms are a common feature of ice-shelves,
and large cracks can form, leading to huge icebergs breaking off the
main shelf into the sea.
This occurred in 1998, when a section of
the Antarctic’s Filchner-Ronne ice-shelf measuring 145km by 50km broke
away, carrying with it a then unoccupied German research station. Two
years ago an iceberg the size of New York broke off the Pine Island
Glacier.
“All ice shelves do this. It’s a natural event,” said Dr
Gudmundsson. “But it’s difficult to say exactly when and how large
these events will be. It’s like trying to predict an earthquake.”

On cracking ice

• Halley VI, British Antarctic Survey research station.
• Opened in 2013.
• Features eight space-age modules.
• On the Brunt ice shelf – a 250km thick slab attached to the Antarctic landmass.
• At risk from a 29km long crack in the ice.

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