Large iceberg breaks away from Antarctica’s Brunt Ice Shelf

Today’s Image of the Day from NASA Earth Observatory features a large iceberg that has broken away from Antarctica’s Brunt Ice Shelf. The rift that spawned the calving event, known as Chasm 1, was first observed in satellite images in September of 2019.

The break was detected on February 26, 2021, and then confirmed the next day with radar images from the European Space Agency’s Sentinel-1A satellite. The giant iceberg, A-74, spans 490 square miles, which is about twice the size of Chicago. 

According to NASA, A-74 broke from the ice shelf northeast of the McDonald Ice Rumple – an area where the flow of ice is impeded by an underwater formation that causes pressure waves, crevasses, and rifts to form at the surface. 

The rift that produced the iceberg rapidly advanced across the ice shelf during the summer of 2020 to 2021.

“I would not have thought that this rift could go zipping across the northeast side of the Brunt Ice Shelf and cause a significant calving – all in a tiny fraction of the time it has taken Chasm 1 to extend toward the ice rumples from the south,” said Christopher Shuman, a glaciologist based at NASA’s Goddard Space Flight Center.

The image was captured on March 1, 2021 by the Operational Land Imager (OLI) on Landsat 8.

Image Credit: NASA Earth Observatory 

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By Chrissy Sexton, Earth.com Staff Writer