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Massive iceberg almost the size of Greater LONDON breaks off Antarctica's Brunt Ice Shelf

The iceberg broke off at a huge fissure that bisected the sea ice, known as Chasm-1 (pictured), which had risen by around 4km every year since 2012

A huge iceberg has broken away from the Brunt Ice Shelf in Antarctica, just 12 miles (19 km) from where British scientists are working at a research station.

The iceberg is 490 feet (150 meters) thick and 600 square miles (1,550 km²) in area – almost the size of Greater London.

It broke off at a huge crack that bisected the sea ice, known as Chasm-1, which had risen about 2.5 miles (4 kilometers) every year since 2012.

GPS sensors began picking up movement at Chasm-1 between 7 p.m. and 8 p.m. Sunday, when it spread out about 40 miles (60 kilometers), across the shelf.

The iceberg broke off at a huge fissure that bisected the sea ice, known as Chasm-1 (pictured), which had risen by around 4km every year since 2012

The iceberg broke off at a huge fissure that bisected the sea ice, known as Chasm-1 (pictured), which had risen by around 4km every year since 2012

GPS sensors began picking up movement at Chasm-1 between 7 p.m. and 8 p.m. Sunday, when it stretched about 40 miles (60 km) long - across the shelf

GPS sensors began picking up movement at Chasm-1 between 7 p.m. and 8 p.m. Sunday, when it stretched about 40 miles (60 km) long – across the shelf

What is a calving?

Glacier calving is a natural phenomenon caused by the forward motion of a glacier that makes its tip unstable.

During a calving, part of the end of a glacier falls off, often forming an iceberg.

The calving of glaciers is often accompanied by a loud crack or rumble before blocks of ice up to 60 meters (200 ft) high break off and crash into the water.

The entry of this ice into the water can cause large and dangerous waves.

Fortunately, all 21 staff working at Halley Research Station with the British Antarctic Survey (BAS) were completely safe and prepared for this eventuality.

Professor Dame Jane Francis, Director of BAS, said: “Measurements of sea ice are taken several times a day using an automated network of high-precision GPS instruments that surround the station.

“These measure how the sea ice deforms and moves, and is compared to satellite images from ESA, NASA and the German TerraSAR-X satellite.

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“All the data is 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 drops in below -58°F (-50°C).’

Glaciologists have confirmed that the area of ​​ice on which the station sits was unaffected by the event.

In 2016, the continued growth of Chasm-1 prompted BAS – the National Polar Research Institute – to move the site 23 kilometers inland.

Chasm-1 (pictured) had been inactive for 25 years until 2012 when satellite monitoring revealed it was starting to move

Chasm-1 (pictured) had been inactive for 25 years until 2012 when satellite monitoring revealed it was starting to move

Although not the largest iceberg to break away from Antarctica, it is the largest chunk the sea ice has lost since observations began over 100 years ago in 1915. Pictured: Chasm -1

Although not the largest iceberg to break away from Antarctica, it is the largest chunk the sea ice has lost since observations began over 100 years ago in 1915. Pictured: Chasm -1

The weekend “calving” was completely natural – not at all related to climate change – and caused by a spring tide.  Calving is a natural phenomenon caused by the forward movement of a glacier making its end unstable

The weekend “calving” was completely natural – not at all related to climate change – and caused by a spring tide. Calving is a natural phenomenon caused by the forward movement of a glacier making its end unstable

The weekend “calving” was completely natural – not at all related to climate change – and caused by a spring tide.

Professor Dominic Hodgson, BAS glaciologist, said: ‘This calving event was expected and is part of the natural behavior of the Brunt Ice Shelf.

“Our science and operations teams continue to monitor the sea ice in real time to ensure it is safe and to maintain the delivery of the science we are undertaking at Halley.”

Calving is a natural phenomenon caused by the forward movement of a glacier making its end unstable.

During a calving, part of the end of a glacier falls off, often forming an iceberg.

It sits on the Brunt Ice Shelf, which floats over the frozen continent and sinks at a rate of about 1.5 miles per year.

It sits on the Brunt Ice Shelf, which floats over the frozen continent and sinks at a rate of about 1.5 miles per year.

Staff are deployed to the station between November and March to maintain the facilities that allow them to monitor the experiments remotely during the winter

Staff are deployed to the station between November and March to maintain the facilities that allow them to monitor the experiments remotely during the winter

HOW ARE SCIENTISTS MONITORING 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 hourly updates.

These include the European Space Agency’s Sentinel 2 satellites, NASA’s Worldview satellites, the United States’ Landsat 8 and TerraSAR-X.

They are also using on-site drone imagery, as well as ground-penetrating radar to image below ground.

The data provided scientists with a number of ways to measure cracks with high precision.

They also used computer models and bathymetric maps to predict how close the pack ice was to calving.

While it’s not the biggest iceberg to break away from Antarctica, it’s the biggest chunk the sea ice has lost since observations began over 100 years ago in 1915.

Chasm-1 had been dormant for at least 35 years before 2012, when satellite monitoring revealed it was beginning to move.

In 2015 and 2016, scientists used ice-penetrating radar technology and satellite imagery to determine the path the fracture might take and how fast it might grow.

In December, Chasm-1 crossed the majority of the ice shelf, marking the start of the calving event.

The iceberg it formed, to be named by the US National Ice Center, is expected to drift in the Weddell Sea, but glaciologists will track its movement.

The Halley VI Research Center is an internationally important platform for atmospheric and space weather observations in a climate-sensitive area.

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It has been unoccupied for the past six winters due to the complex glaciological situation which makes the impact of calvings unpredictable.

However, personnel are deployed there between November and March to maintain the facilities that allow the experiments to be monitored remotely during the winter.

Those currently on site must be picked up by plane around February 6.

The Brunt Ice Shelf is made up of glacier ice that flowed from land in Antarctica and floated out to sea.

The Brunt Ice Shelf is made up of glacier ice that flowed from land in Antarctica and floated out to sea.

All 21 staff working at Halley Research Station (pictured) with the British Antarctic Survey were completely safe and had prepared for this eventuality

All 21 staff working at Halley Research Station (pictured) with the British Antarctic Survey were completely safe and had prepared for this eventuality

This is the second major calving from the Brunt Ice Shelf in the past two years, with the first occurring in February 2021.

In November 2020, a major fracture – called the North Rift – began cutting its way through the ice and continued to expand until the start of the new year.

This accumulated in a 490 square mile (1,270 km²) iceberg, called A74, breaking away from the vast floating ice shelf and drifting into the Weddell Sea.

The Brunt Ice Shelf is made up of glacier ice that originally fell as snow on Antarctica and flowed from the land to the sea.

It flows at a rate of up to 2 km per year towards the west towards the sea where, at irregular intervals, it breaks away from the icebergs.

In 2021, an iceberg nearly 500 square miles in size grazed west of the Brunt Ice Shelf, but it didn’t split Chasm-1.

It was feared that if it had hit West Brunt harder, it would eventually cause the main ice shelf block to break off and create the new iceberg.

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