BAS finds ‘subglacial’ volcanoes and lakes
Glaciologists and geologists from the British Antarctic Survey (BAS)
have identified two important geographical features that exist beneath
the West Antarctic Ice Sheet and are invisible to the naked eye.
A team led by Hugh Corr of the BAS used an aircraft fitted with specialised radar equipment to bounce waves through the ice and identify a subglacial layer of ash that extends across an area the size of Wales. According to the scientists, the ash layer proves that a volcanic eruption occurred beneath the ice sheet some 2,000 years ago.
‘Our techniques also allow us to put a date on the eruption, determine how powerful it was and map out the area where ash fell,’ Corr said. ‘It blew a substantial hole in the ice sheet and generated a plume of ash and gas that rose around 12 kilometres in the air.’
The eruption, believed to have been the largest in the region in 10,000 years, is also thought to have accelerated basal melting beneath the nearby Pine Island Glacier and may explain why the glacier’s flow towards the coast has increased in recent decades.
Another BAS team is on the West Antarctic Ice Sheet conducting geophysical surveys of Lake Ellsworth, an ancient subglacial lake the size of Windermere that may have lain isolated for hundreds of thousands of years. One of around 150 such lakes in the region, it could harbour vital clues about early microbial lifeforms and past climates, as well as the region’s future.
Professor Martin Siegert of the University of Edinburgh, project principal investigator for the International Polar Year, said: ‘Radar measurements made from previous aircraft surveys suggest the lake is connected to others and could drain ice from the West Antarctic Ice Sheet to the ocean, contributing to sea level rise.’
If the initial surveys of Lake Ellsworth are deemed successful, the BAS will attempt to drill through more than three kilometres of ice to collect samples of the lake’s water, which, curiously remains in a liquid state. This is possibly due to a combination of heat from the Earth’s core emanating from the bedrock below and the insulating effect of the ice above.
April 2008
A team led by Hugh Corr of the BAS used an aircraft fitted with specialised radar equipment to bounce waves through the ice and identify a subglacial layer of ash that extends across an area the size of Wales. According to the scientists, the ash layer proves that a volcanic eruption occurred beneath the ice sheet some 2,000 years ago.
‘Our techniques also allow us to put a date on the eruption, determine how powerful it was and map out the area where ash fell,’ Corr said. ‘It blew a substantial hole in the ice sheet and generated a plume of ash and gas that rose around 12 kilometres in the air.’
The eruption, believed to have been the largest in the region in 10,000 years, is also thought to have accelerated basal melting beneath the nearby Pine Island Glacier and may explain why the glacier’s flow towards the coast has increased in recent decades.
Another BAS team is on the West Antarctic Ice Sheet conducting geophysical surveys of Lake Ellsworth, an ancient subglacial lake the size of Windermere that may have lain isolated for hundreds of thousands of years. One of around 150 such lakes in the region, it could harbour vital clues about early microbial lifeforms and past climates, as well as the region’s future.
Professor Martin Siegert of the University of Edinburgh, project principal investigator for the International Polar Year, said: ‘Radar measurements made from previous aircraft surveys suggest the lake is connected to others and could drain ice from the West Antarctic Ice Sheet to the ocean, contributing to sea level rise.’
If the initial surveys of Lake Ellsworth are deemed successful, the BAS will attempt to drill through more than three kilometres of ice to collect samples of the lake’s water, which, curiously remains in a liquid state. This is possibly due to a combination of heat from the Earth’s core emanating from the bedrock below and the insulating effect of the ice above.
April 2008
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