Massive iceberg almost the size of Greater London breaks off Antarctica’s Brunt Ice Shelf
A humongous iceberg has broken off the Brunt Ice Shelf in Antarctica, just 12 miles (19 km) away from where British scientists are working in a research station.
The iceberg has a thickness of 490 feet (150 metres) and an area of 600 square miles (1,550 km²) – almost the size of Greater London.
It broke off at a huge crack that bisected the ice shelf, known as Chasm-1, which had been growing by about 2.5 miles (4 kilometers) each year since 2012.
GPS sensors began to pick up movement at Chasm-1 between 7pm and 8pm on Sunday, when it extended to roughly 40 miles (60 kilometers), across the entire shelf.
The iceberg broke off at a huge crack that bisected the ice shelf, known as Chasm-1 (pictured), which had been growing by about 2.5 miles (4 km) each year since 2012.
GPS sensors began to pick up movement at Chasm-1 between 7pm and 8pm on Sunday, when it extended to roughly 40 miles (60 km) long – across the entire shelf.
What’s a calving event?
Glacier calving is a natural occurrence caused by the forward motion of a glacier making its end unstable.
During a calving event, part of the end of a glacier drops off, often forming an iceberg.
Calving of glaciers is often accompanied by a loud cracking or booming sound before blocks of ice up to 60 meters (200 ft) high break loose and crash into the water.
The entry of this ice into the water can cause large and dangerous waves.
Fortunately, all of the 21 staff working at the Halley Research Station with the British Antarctic Survey (BAS) were completely safe, and had been preparing for this eventuality.
Professor Dame Jane Francis, Director of BAS, said: ‘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 -58°F (-50 °C).’
The glaciologists have confirmed that the area of ice the station is situated on remains unaffected by the event.
In 2016, continuous growth of Chasm-1 prompted the BAS – the national polar research institute – to relocate the site 14 miles (23 kilometers) inland.
Chasm-1 (pictured) had lain dormant for the 25 years prior to 2012, when satellite monitoring revealed it was starting to move.
While this won’t be the largest iceberg to split off from Antarctica, it’s the biggest chunk the ice shelf has lost since observations began over 100 years ago in 1915. Pictured: Chasm-1
The weekend’s ‘calving event’ was completely natural – not at all linked to climate change – and caused by a spring tide. Calving is a natural occurrence caused by the forward motion of a glacier making its end unstable.
The weekend’s ‘calving event’ was completely natural – not at all linked to climate change – and caused by a spring tide.
Professor Dominic Hodgson, BAS glaciologist, said: ‘This calving event has been expected and is part of the natural behavior of the Brunt Ice Shelf.
‘Our science and operational teams continue to monitor the ice shelf in real-time to ensure it is safe, and to maintain the delivery of the science we undertake at Halley’.
Calving is a natural occurrence caused by the forward motion of a glacier making its end unstable.
During a calving event, part of the end of a glacier drops off, often forming an iceberg.
The Halley VI Research Center (pictured) is an internationally important platform for atmospheric and space weather observations in a climate-sensitive zone.
It sits on the Brunt Ice Shelf, that floats on the frozen continent and flows at a rate of about 1.5 miles per year.
Staff are deployed at the station between November and March to maintain the facilities that allow them to monitor experiments remotely during the winter.
HOW DO SCIENTISTS MONITOR THE BRUNT ICE SHELF?
Scientists use a network of 16 GPS instruments to measure any deformation of the Brunt Ice Shelf, which causes cracks, which report updates every hour.
These include the Sentinel 2 satellites from the European Space Agency, NASA Worldview satellites, US Landsat 8 and TerraSAR-X.
They also utilize on-site drone footage, as well as ground penetrating radar to image the subsurface.
The data has provided scientists with a number of ways to measure any cracks with high precision.
They have also used computer models and bathymetric maps to predict how close the ice shelf was to calving.
While this won’t be the largest iceberg to split off from Antarctica, it’s the biggest chunk the ice shelf has lost since observations began over 100 years ago in 1915.
Chasm-1 had lain dormant for at least 35 years prior to 2012, when satellite monitoring revealed it was starting to move.
In 2015 and 2016, scientists used ice-penetrating radar technologies and satellite images to determine the path the fracture could take, and the speed it could grow.