A gigantic iceberg measuring around 1,550 square kilometres, more than twice the size of the city of Mumbai, broke off from the 150 metres-thick Brunt Ice Shelf in Antarctica, according to the British Antarctic Survey (BAS). The breakoff took place on January 23 between 12.30 AM and 1.30 AM IST. The iceberg split from the ice shelf when a crack known as Chasm-1 fully extended through the shelf. This is the second major “calving” incident in the area in the last two years, and it happened a decade after BAS scientists first detected the growth of vast cracks in the ice. Ice calving refers to the breaking off of ice chunks from the edge of an ice shelf or glacier. The Brunt Ice Shelf has a complex glaciological structure, and the impact of calving events is unpredictable. BAS has a research station located on the Brunt Ice Shelf called the Halley Research Station. The UK’s national polar research institute took the precaution of relocating Halley Research Station in 2016 when Chasm-1 began widening. “Our glaciologists and operations teams have been anticipating this event. Measurements of the ice shelf are carried out multiple times a day using an automated network of high-precision GPS instruments that surround the station. These measure how the ice shelf is deforming and moving, and are compared to satellite images from ESA, NASA and the German satellite TerraSAR-X. All data are sent back to Cambridge for analysis, so we know what is happening even in the Antarctic winter – when there are no staff on the station, it is dark for 24 hours and the temperature falls below minus 50 degrees C,” said Jane Francis, director of BAS, in a press statement. In October 2016, a new crack known as Halloween Crack was detected around 17 kilometres North of the Halley Research Station. By 2020, another crack appeared further north and an iceberg (now known as A74) separated from the ice shelf in February 2021. A74 has now drifted away from the Ice Shelf into the Weddell Sea. The new iceberg that formed on January 23 is slightly larger than A74, and according to BAS, it will likely follow the path of A74 along the Antarctic Coastal Current.
