A23a: Monster iceberg just shy of a trillion tonnes

Scientists now have good numbers to describe the true scale of the world's biggest iceberg, A23a.

Satellite measurements show the frozen block has a total average thickness of just over 280m (920ft).

Combined with its known area of 3,900 sq km (1,500 sq miles), this gives a volume of roughly 1,100 cubic km and a mass just below a trillion tonnes.

The iceberg, which calved from the Antarctic coast in 1986, is about to drift beyond the White Continent.

It has reached a critical point in its journey, researchers say, with the next few weeks likely to decide its future trajectory through the Southern Ocean.