What a crack in a glacier looks like

You read and hear about glaciers cracking. Here’s what one of those cracks looks like.

This is a rift in Antarctica’s Pine Island Glacier. The crack happened in October 2011, and scientists think that part of the glacier will break off and become an enormous iceberg – though they aren’t exactly sure when it will happen.

Pine Island glacier has cracked and will spawn a giant iceberg

Image Credit: NASA

In October 2011, researchers flying in NASA’s Operation IceBridge campaign made the first-ever detailed, airborne measurements of a major iceberg calving event while it was in progress. The above image is a still frame captured from a three-dimensional, virtual flight through the new rift in the Pine Island Glacier.

Four months later, the IceBridge team has mapped the crack in Antarctica’s Pine Island Glacier in a way that allows glaciologists and the rest of us to fly through the icy canyon. The animation (below) was created by draping aerial photographs from the Digital Mapping System—a still camera with very precise geolocation ability—over data from the Airborne Topographic Mapper—a scanning laser altimeter that measures changes in the surface elevation of the ice.

Cracked Ice from EarthSky on Vimeo.

The crack formed in the ice shelf that extends from one of West Antarctica’s fastest-moving glaciers. The path of the crack in this animation stretches roughly 18 miles (30 kilometers) in length (the actual crack is much longer), with an average width of 240 feet (about 80 meters); it was 820 feet (250 meters) at its widest. The canyon ranged from 165 to 190 feet deep (50 to 60 meters), with the floor being roughly at the water line of the Amundsen Sea. Radar measurements suggested the ice shelf is about 1,640 feet (500 meters) feet thick, with only 165 to 190 feet of that floating above water and the rest submerged.

More about Pine Island glacier: Sophie Nowicki on weak underbelly of West Antarctic Ice Sheet

Scientists have been waiting for the crack to propagate through the rest of the ice shelf and release an iceberg, which they estimate could span 300 to 350 square miles (up to 900 square kilometers). If it does not split off soon, however, the sea ice that forms with the onset of southern winter might keep the ice chunk trapped against the coast for a while.

Read more from NASA’s Earth Observatory

March 1, 2012

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