A joint Australian-French study has discovered the calving of a large iceberg from the Mertz Glacier in the Australian Antarctic Territory.

The iceberg - 78 kilometres long with a surface area of roughly 2,500 square kilometres, about the size of Luxembourg - broke off the Mertz Glacier after being rammed by another iceberg, 97 kilometres long.

The Mertz Glacier had a large crack in it for two decades. A second crack developed opposite the first in the early part of the 21st century. The collaboration studied whether these two cracks would eventually meet, and the processes that would lead to the calving of an iceberg.

Background

The joint French-Australian team that detected this calving event has been working on a project called "CRACICE" (Cooperative Research into Antarctic Calving and Iceberg Evolution). The iceberg has an area of about 2,550 square kilometers, an overall length of 78 kilometers, width of 33 to 39 km, and represents about half the length of the glacier tongue. Satellite imagery shows the iceberg separation occurred on February 12-13.

The CRACICE team is carrying out a long-term study on how fractures developing in the Mertz Glacier Tongue lead to iceberg calving, and the fate of the icebergs and remaining glacier tongue.

Their work involves surveys using satellite data and GPS beacons deployed on the glacier to measure the evolution of the rifts and the calving process. The team has followed the development of two major rifts cutting across the tongue, from opposite sides, over many years. The rifts had almost joined, when a similarly massive iceberg, B-9B, collided with the eastern flank of the tongue leading to the final separation.

"The Mertz Glacier tongue breaks off 20 February 2010. (Credit: Photo by Neal Young, Australian Antarctic Division)"

Source: Antarctic Climate and Ecosystems