Brunt Ice Shelf movement

What this project does

This project monitors glaciological changes on the Brunt Ice Shelf, home to Halley Research Station.

The ice shelf is around 150 metres thick. Scientists classify very large cracks that go all the way to the sea as “chasms”. Narrower cracks of indeterminate depth are called crevasses.

The project uses a combination of in situ instruments, satellite imagery, drones, and numerical models. The aim is to track ice shelf changes and assess risks to operations and infrastructure.

GPR (Ground Penetrating Radar) survey on the Brunt Ice Shelf

Why this matters

In 2012, satellite monitoring revealed movement in Chasm 1, which had been dormant for at least 35 years. Chasm 1 continues to grow, impacting the safety and operation of Halley VI. In 2016/17, the research station was successfully relocated to a safer area.

In October 2016, a new crack called the ‘Halloween Crack’ appeared 17 km north of the station. It crosses the route sometimes used to resupply Halley. Together, Chasm 1 and Halloween Crack form a complex glaciological situation. The final outcome is uncertain. Station closure during recent winters has been a precautionary measure when evacuation would be difficult.

Brunt Ice Shelf, Antarctica

How the project works

Ice monitoring technologies

The Brunt Ice Shelf is one of the most closely observed ice shelves on Earth. A network of 15 GPS instruments records ice deformation daily. Satellite images from Copernicus Sentinel 1 & 2, NASA Worldview, Landsat 8, and TerraSAR-X track rift tips and ice velocity. Ground-penetrating radar and drone footage provide detailed measurements of crack growth.

Data from these sources are used in computer models and bathymetric maps to predict iceberg calving. The Autonomous phase-sensitive Radio Echo Sounder (ApRES) provides the primary early warning system. It measures the width of Chasm 1 every two hours and informs daily station operations.

Seabed bathymetry and grounding

A major calving event is likely as Chasm 1 approaches the McDonald Ice Rumples. The ice shelf’s future depends on the chasm’s trajectory. If it moves upstream of the rumples, the ice shelf could detach from the bed. If it moves downstream, the ice shelf remains structurally intact.

Ground truthing and field surveys

Glaciologists use ice-penetrating radar to map Chasm 1 and estimate its likely path and speed. They continuously monitor cracks and crevasses using radar, GPS, and satellite imagery. The 2018/19 field season updated estimates for Chasm 1 growth. Routes previously used to resupply Halley are avoided as new cracks emerge.

BAS Scientist checking the data recording during a GPR survey on the Brunt Ice Shelf

Science objectives

The project aims to:

• monitor daily ice deformation using GPS instruments
• track growth and movement of Chasm 1 and Halloween Crack
• map ice shelf features with radar, satellites, and drones
• model calving events and assess operational risks
• inform safe station operations and infrastructure planning

Who is involved

British Antarctic Survey leads the monitoring program. Teams include glaciologists, technical staff, and operational support at Halley Research Station. They work closely with satellite data providers and modelling experts.

The aim of this project is to provide the best scientific intelligence to:

• enable safe operation of Halley VI Research Station through its lifetime
• use the most up-to-date satellite and ground-based technologies to inform operational decision-making
• inform other long-running ice dynamics research programmes

The future of the ice shelf depends on the trajectory of Chasm 1. If it progresses upstream of the McDonald Ice Rumples (MIR), the ice shelf could become structurally detached from the bed. The alternative is that Chasm 1 progresses downstream of the pinning point at the ice rumples, the ice shelf remains in contact with the bed, and retains its structural integrity. To provide scientific evidence for an assessment of the future stability of the ice shelf and its infrastructure BAS researchers will:

• make direct measurements of the thickness of the ice shelf and depth to the bed in a transect away from the MIR to calibrate existing radar and bathymetry data;
• measures the growth of rifts and the resulting behaviour of ice upstream of these rifts.

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