* Astronomy

A remote South Atlantic volcano, trapped under polar ice, is erupting in spectacular fashion.

This is the first time that researchers have had a chance to watch an Antarctic lava flow in action.

"I'd give my right arm to be down there now. It's very rare that we get to make direct observations of eruptions under ice sheets" - John Smellie, a volcano expert at the British Antarctic Survey in Cambridge, UK.

Montagu Island is part of the volcanic South Sandwich Islands, which lie about 2,000 kilometres from mainland Antarctica and are dependent territories of the United Kingdom.
Montagu's active volcano, the 1375 meter high Mount Belinda, has been grumbling away since late 2001, but for most of that time has produced little more than smoke and ash.

"Then suddenly, towards the end of September, the crater filled with lava and it has been running ever since. In the past four weeks, it has released half a million cubic metres of lava" - John Smellie.

The island, which is about 12 kilometres across, has so far expanded by about 0.2 square kilometres, or roughly 30 football pitches. Meanwhile the melting ice sheet is pouring huge quantities of water into the ocean.

Images of the eruption were snapped by NASA's Earth-monitoring satellite Terra, which passes over the island about twice a day and takes high resolution snaps twice a month. Scientists were alerted to the event by a computerized detection system called MODVOLC. The system was developed at the Hawaii Institute of Geophysics and Planetology in Manoa to churn through Terra's data in search of interesting hot spots.
Smellie normally studies Antarctic rock formations to find out how eruptions have affected the growth and retreat of ice sheets over the past 30 million years.


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This is a false-colour image acquired on December 7, 2003, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), another sensor onboard Terra. The image (made using ASTER bands 3, 2, and 1) shows the eruption of Mount Belinda has progressed steadily for an impressive two years, with low-level ash emission and a 2-km long lava flow emplaced on the ice shelf on the north side of the summit.



The South Sandwich Islands, situated approximately between the southern tip of South America and mainland Antarctica, comprise one of the most remote volcanic areas on Earth, and are probably not viewed on more than a few days each year. Due to this inaccessibility, satellite monitoring is the only viable means to keep track of this highly active volcanic arc.

"But how hot rock interacts with ice is so poorly understood. This opportunity to monitor a live eruption and see how it affects ice cover is priceless" - John Smellie.

Smellie hopes to hitch a ride over the island on a Royal Air Force aeroplane, which will fly from the Falkland Islands next March.

"It will be the highlight of my career" - John Smellie.

Although satellite images are useful, a fly-by will provide a much more accurate picture of the terrain.
The changes to the area will be dramatic. A relatively small eruption in 1996 beneath the Vatnajökull glacier at Gjálp, Iceland, released a flood that became the second biggest freshwater discharge on the planet at the time, beaten only by the River Amazon.
When lava hits ice and snow, it can also create dangerous volcanic mud flows.

"These data should help with our understanding of these processes in general" - Matt Patrick, part of the Hawaii team that got the first glimpse of the satellite images.

Details of the eruption are presented in the latest issue of the Bulletin of Volcanology.