14 DAY TRIAL // Under the 3,000 m (10,000 ft) thickness of the Antarctic ice sheet, scientists have found proofs of a spectacular volcanic eruption. This happened under the Pine Island Glacier (in the area of the West Antarctic Ice Sheet) about 2,000 years ago (in 325 B.C.) and the under-ice volcano is still active, having a 'volcanic explosion index' of 3-4.
Currently, the heat expelled from the volcano melts the surrounding ice, creating a water source that lubricates the base of the ice sheet, speeding up its slip into the sea.
The team from British Antarctic Survey (BAS) encountered a layer of ash caused by the 'subglacial' volcano, by employing airborne ice-sounding radar. The area affected by the ancient explosion, in the Hudson Mountains at latitude 74.6?South, longitude 97?West, is larger than Wales.
"The discovery of a 'subglacial' volcanic eruption from beneath the Antarctic ice sheet is unique in itself. But 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. We believe this was the biggest eruption in Antarctica during the last 10,000 years. It blew a substantial hole in the ice sheet, and generated a plume of ash and gas that rose around 12 km into air", said lead author Hugh Corr of the BAS.
Glaciers flow slowly like giant rivers of ice into the sea around Antarctica, breaking up into large floating chunks called icebergs.
"The flow of this glacier (the Pine Island Glacier) towards the coast has sped up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters", said co-author Professor David Vaughan (BAS).