A massive iceberg that recently broke away from the Brunt Ice Shelf earlier this month has been spotted in a near-miss event with the rest of the ice shelf. At 490 square miles (1,270 square kilometers), the iceberg, dubbed A-74, is roughly 1 and a half times the size of Greater Paris, or if you’d prefer, a slightly smaller Los Angeles, and it has remained fairly close to its source ice shelf over the last six months.
Earlier this month, strong east winds had spun the iceberg around the western tip of the Brunt Ice Shelf resulting in it brushing past the ice shelf before continuing its route southwards.
The near-collision event was picked up with radar images from the Copernicus Sentinel-1 mission. Data of this kind is invaluable for glaciologists during the darker months of Antarctica since the region is so remote.
Radar imagery can be taken and analyzed regardless of the weather or seasonal darkness of the region regardless of whether it is day or night. This allows for continuous imaging during what is now Antarctic mid-winter.
A collision could have been catastrophic for the Brunt Ice Shelf
This event is interesting but could have proved to be catastrophic for the ice shelf had A-74 hit it with significant force. The Brunt Ice Shelf has been the subject of study by glaciologists for years who have been monitoring the formation and extensions of large cracks, technically known as rifts, on the shelf.
The largest of these, Chasm 1, is a large crack that runs northwards from the southernmost part of the 93-mile-thick (150 m) Brunt Ice shelf. Being hit at speed by something as large as A-74 may well have triggered the release of a new 656-square mile (1,700 square km) iceberg.
Thankfully, this did not happen, and while A-74 did brush the shelf, at the time of writing the potential iceberg remains firmly attached to the vicinity of McDonald Ice Rumples, where the ice shelf is grounded on the seabed.
“The nose-shaped piece of the ice shelf, which is even larger than A-74, remains connected to the Brunt Ice Shelf, but barely. If the berg had collided more violently with this piece, it could have accelerated the fracture of the remaining ice bridge, causing it to break away. We will continue to routinely monitor the situation using Sentinel satellite imagery,” said the ESA’s Mark Drinkwater.
This part of the Antarctica ice shelf is so unstable that the British Antarctic Survey closed their Halley VI Research Station and re-positioned it to a more secure location, around 12.4 miles (20 km) away from Chasm 1 back in 2017.
This station is made up of eight interlinked pods built on skis which allows the pods to be easily moved in case of unstable ice or new chasms forming on the ice shelf.
For now, the Brunt Ice Shelf is out of immediate danger of a possible impact from A-74, but rest assured that glaciologists will continue to monitor the situation.