As an iceberg more than twice the size of Wellington begins to break away from Antarctica, scientists have made it possible to get an up close and personal view of the icy marvel in action.

A vast crack is forming on the ice continent, wider than the distance between Auckland and Taupo at points, and Nasa has created a virtual flythrough of the canyon.

By draping aerial photographs over data from a scanning laser altimeter - which measures changes in the surface elevation of the ice - the scientists created the dramatic virtual video.

The crack, located on Pine Island Glacier, was discovered on a flight on October 14 last year during NASA's six-week Icebridge project. Scientists then measured the growth of the 30km long rift - thought to be several meters per day - on subsequent flights.

It measures around 55m deep above sea level, but scientists expect there is another 450m submerged in the ocean.

It is unsure when the 900 km sq iceberg will break free, but if it does not split off soon the onset of winter might keep the ice chunk trapped against the coast for months.

- NZ Herald Online Staff